# Airflow vs static pressure fans. Are they a scam?



## The red spirit (Jul 7, 2021)

As far as I understand this is the formula of fan airflow:
air moved = rpms*volume of air that fan blades catch per revolution*static pressure of fan

It seems that fan static pressure and airflow is very similar to car engine's horsepower, revs and torque. So static pressure in fan is like torque in car and horsepower in car is like airflow in fan. Since fans usually aren't made thicker and most common size of them is 120mm, a hypothetical fan that runs at 1400 rpm, but one is made to be optimized for air flow and other is made to static pressure. That happens if you change blades. However, to achieve higher pressure, some cfm has to be sacrificed, therefore fan is able to provide lower level of air flow, but through more obstructions, meanwhile airflow optimized fan is overall better performing in terms of cfm (and probably in terms of noise, since pressure fans have heavier blades and they vibrate more when spinning), however such fan in theory shouldn't cope well with obstructions. However, from as much as I have observed, a fan blades don't really affect fan performance much. I'm starting to think that higher static pressure fans may have only slightly higher static pressure (makes sense, since a fan isn't a good air pump, due to gaps and due to looking nothing like a proper Archimedes screw) and thus in many practical scenarios higher static pressure just simply fail to deliver any proper advantage over basic airflow optimized fan. Meanwhile air flow fans pretty much always generate enough pressure, so there's no need for any special design. Are these observations true or not?

Side note:
it seems that static pressure optimized fans have a much better laminar flow:









See? Nidec has pretty much ideal straight laminar flow, instead of very turbulent and not straight flow of typical fan, which yo can see here (certainly not the best video, but I have seen that stuff somewhere else, it's just so hard to find such stuff again):









Also I have some generic 7 blades and with hand I can feel that air mostly flows from blade edge and flow isn't straight, but but it is like 25 degrees sideways. Not all of it isn't straight, but a good portion of it. Anyway, I have no idea if laminar flow is preferred and is any better than turbulent flow, as far as I know from car aerodynamics, laminar should be better, but since computer fan isn't pushing out air at high speed, it probably doesn't matter much.


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## MentalAcetylide (Jul 9, 2021)

Maybe you're making this more complex than it needs to be or maybe not. I'm not all that familiar with the physics behind fans as its been a while for me, but in general, more fan blades = less static pressure = less noise. You want more static pressure from a fan if you need to push air through things such as radiators, hard drive cages and/or similarly situated components inside a case. High static pressure usually means more CFM air being moved by a fan that has fewer blades & spins faster, but the tradeoff is going to be more dBs. 

This is just a guess, but turbulent flow(depending on how "turbulent") just throws air around in a disorganized manner and is probably more suited for cases that don't have a lot of obstructions inside while laminar would work great for cases that, for example, have 3 fans on the bottom pulling air into the case and 3 fans on the top expelling air out of the case.


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## Shrek (Jul 9, 2021)

The red spirit said:


> Anyway, I have no idea if laminar flow is preferred and is any better than turbulent flow, as far as I know from car aerodynamics, laminar should be better, ...


Turbulent should pick up heat better from a heat sink, but bearing life is also an important consideration in my opinion.

I seem to recall that counter rotating fans are more efficient, but I imagine they are also more noisy.


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## 80251 (Jul 9, 2021)

MentalAcetylide said:


> Maybe you're making this more complex than it needs to be or maybe not. I'm not all that familiar with the physics behind fans as its been a while for me, but in general, more fan blades = less static pressure = less noise. You want more static pressure from a fan if you need to push air through things such as radiators, hard drive cages and/or similarly situated components inside a case. High static pressure usually means more CFM air being moved by a fan that has fewer blades & spins faster, but the tradeoff is going to be more dBs.
> 
> This is just a guess, but turbulent flow(depending on how "turbulent") just throws air around in a disorganized manner and is probably more suited for cases that don't have a lot of obstructions inside while laminar would work great for cases that, for example, have 3 fans on the bottom pulling air into the case and 3 fans on the top expelling air out of the case.



Three bladed refrigeration Delta fans have very little static pressure (and the below fan is 52mm thick):

https://www.delta-fan.com/eub1312me.html

This delta 120x25mm fan produces more static pressure at a lower RPM than the three-bladed fan above:
https://www.delta-fan.com/AFB1212L-F00.html


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## looniam (Jul 9, 2021)

i love that guy










my understanding fwiw,  high air flow are more likely to have several more blades than a high static fan 11-9 compared to 7-9 blades and the space between the blades will be larger. i've seen brochures/marketing about pitch and curvature/whatever but i just file that as . .marketing.


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## MentalAcetylide (Jul 9, 2021)

80251 said:


> Three bladed refrigeration Delta fans have very little static pressure (and the below fan is 52mm thick):
> 
> https://www.delta-fan.com/eub1312me.html
> 
> ...


I think you need to recheck the spec sheets on those fans. The first link for the 3-bladed one shows a static pressure of 32.60 mmH2O vs. the second link for the 7-bladed fan which only has 3.93 mmH2O. 
32.60 mmH2O > 3.93 mmH2O, meaning the 3-bladed fan has higher static pressure.


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## The red spirit (Jul 9, 2021)

Andy Shiekh said:


> Turbulent should pick up heat better from a heat sink, but bearing life is also an important consideration in my opinion.
> 
> I seem to recall that counter rotating fans are more efficient, but I imagine they are also more noisy.


Eh, bearing life span barely matters in reality. It's not that it doesn't matter, but because even very basic and cheap sleeve fans survive for more than decade and their lifespan could be extended with re-oiling them and keeping them clean. Pretty much anything more than sleeve fan is overkill. Noise and maybe performance are the main factors for choosing certain bearings and the classical orientation problem (you shouldn't mount sleeve bearing fans horizontally, although that observation is more theoretical than empirical. I personally have ATi X800 Pro and ATi X800 XT PE cards, both have sleeve bearing fans and they worked for a long time in vertical position, fans still work).


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## The red spirit (Jul 9, 2021)

looniam said:


> i love that guy


I like him too. I legit have golf ball dimpled fans myself (Silverstone Globe 120mm 1200 rpm). I got them with Silverstone Grandia GD05B case. Specs say that they are 20dB loud at 1200 rpm, which is pretty much identical to the most generic 7 blade fan, like Cooler Master Sl1. At least in terms of noise and rpms, they are the same. I haven't noticed anything else either. It seems that golf ball pattern doesn't do anything, other than looking odd.



looniam said:


> my understanding fwiw,  high air flow are more likely to have several more blades than a high static fan 11-9 compared to 7-9 blades and the space between the blades will be larger. i've seen brochures/marketing about pitch and curvature/whatever but i just file that as . .marketing.


I noticed that too, but then we have outliers like some crazy Noctuas, like this one:





Which, at least according to their specification sheet, is better for CFMs than CM Sl1, but at same time, it's is 2 dB quieter and fails to produce as much pressure, as it improves airflow. And this is just 7 blader with different angle and blade shape.


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## 80251 (Jul 9, 2021)

MentalAcetylide said:


> I think you need to recheck the spec sheets on those fans. The first link for the 3-bladed one shows a static pressure of 32.60 mmH2O vs. the second link for the 7-bladed fan which only has 3.93 mmH2O.
> 32.60 mmH2O > 3.93 mmH2O, meaning the 3-bladed fan has higher static pressure.


3 bladed 126mm fan @ 2000RPM from datasheet: 0.139inchH2O (which equates to 3.53mm-H2O according to http://www.worldwidemetric.com/measurements.html)
7 bladed 120mm fan @ 1900RPM from datasheet: 0.154inchH2O (which equates to 3.93mmH2O according to the same website)

32.6mm-H2O of static pressure out of an 126mm axial fan spinning at 2000 RPM is IMPOSSIBLE. If you look at the datasheet the P-Q graph for the 3-bladed delta fan quotes a pressure figure in Pascals of of 34 Pa. Pascals <> mm-H20 as indicated here:
https://www.sensorsone.com/pressure-converter/


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## The red spirit (Jul 9, 2021)

MentalAcetylide said:


> This is just a guess, but turbulent flow(depending on how "turbulent") just throws air around in a disorganized manner and is probably more suited for cases that don't have a lot of obstructions inside while laminar would work great for cases that, for example, have 3 fans on the bottom pulling air into the case and 3 fans on the top expelling air out of the case.







Apparently, CM's static pressure design with long blades is also good at laminar flow. As I understand, turbulent flow is slow flow and in case, disorganization means that it just ends up everywhere, where it shouldn't be, therefore laminar is always preferred. Those two fans are Silencio FP 120 PWM and BladeMaster 120, they don't match in terms of rpms, so for spec comparison I will use blade equivalent MasterFan Pro AP in quiet mode. And for comparison let's add the most generic 7 blade Noiseblocker BlackSilent 120 XL-P:
rpm 2250 vs 2000 vs 2000
cfm 53.5 vs 76.8 vs 75.3
pressure (mmH2O) 3.14 vs 3.90 vs 2.79
noise (dBa) 30 vs 32 vs 31.7

And the conclusion is that, the more cfm fan produces, the higher pressure will be at same noise level. Pressure optimized fan may be more helpful than airflow one at lower rpms, but at 2000 rpms airflow fans are always better. 

To test that theory, I will compare Corsair's AF with SP fan spec sheets. Here they are
rpm 1500 vs 1400
cfm 52 vs 47.7
pressure (mmH2O) 1.45 vs 1.46
noise (dBa) 26 vs 28 

And while Corsair claims that both are static pressure designs, from pictures you can see that SPs technically should be more pressure oriented. And in every aspect SPs are just worse. (Side note: Corsair has really went downhill fast, they don't seem to be reputable brand anymore).


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## OneMoar (Jul 9, 2021)

two sides of the same coin


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## MentalAcetylide (Jul 9, 2021)

80251 said:


> 3 bladed 126mm fan @ 2000RPM from datasheet: 0.139inchH2O (which equates to 3.53mm-H2O according to http://www.worldwidemetric.com/measurements.html)
> 7 bladed 120mm fan @ 1900RPM from datasheet: 0.154inchH2O (which equates to 3.93mmH2O according to the same website)
> 
> 32.6mm-H2O of static pressure out of an 126mm axial fan spinning at 2000 RPM is IMPOSSIBLE. If you look at the datasheet the P-Q graph for the 3-bladed delta fan quotes a pressure figure in Pascals of of 34 Pa. Pascals <> mm-H20 as indicated here:
> https://www.sensorsone.com/pressure-converter/


Ok, sorry about that, they have a typo on their specs sheet. Anyway, try comparing two fans that have the same dimensions, same max. rpm, with different number of blades like this: 
7 blades, 120x120x25, 121.8 m^3/hr, 3.94mmH2O: NF-F12 industrialPPC 
9 blades, 120x120x25, 102.1 m^3/hr, 2.34mmH2O: NF-A12x25 PWM

Now, I could be wrong since fan blade orientation also plays a role, but comparing the specs between the two fans, the 7-bladed fan spinning at 2k rpm has a higher static pressure than the 9-bladed fan spinning at the same rpm.



The red spirit said:


> Apparently, CM's static pressure design with long blades is also good at laminar flow. As I understand, turbulent flow is slow flow and in case, disorganization means that it just ends up everywhere, where it shouldn't be, therefore laminar is always preferred. Those two fans are Silencio FP 120 PWM and BladeMaster 120, they don't match in terms of rpms, so for spec comparison I will use blade equivalent MasterFan Pro AP in quiet mode. And for comparison let's add the most generic 7 blade Noiseblocker BlackSilent 120 XL-P:
> rpm 2250 vs 2000 vs 2000
> cfm 53.5 vs 76.8 vs 75.3
> pressure (mmH2O) 3.14 vs 3.90 vs 2.79
> ...


I guess each has their pros and cons. I've heard arguments against turbulent something to the effect of having "warm pockets" in the case & laminar with not enough air hitting everything in the case. If it keeps my stuff at reasonable temperatures, regardless of the workload, I'm a crappy hamper... err, happy camper!


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## 80251 (Jul 9, 2021)

@MentalAcetylide
Of course the blade design of both those Noctua fans is obviously different. Fewer blades can have a greater pitch, thus increasing static pressure, but that doesn't help the 126x52mm delta 3-blade fan.

I don't know anyone who has personally used one of those three-bladed fans -- they're commonly used in refrigeration. I always thought they would be good exhaust fans because they still have a good CFM rating and are quiet too.


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## Ominence (Jul 9, 2021)

server fans are mostly pressure based fans so that's what you need. high air flow fans are cheap to engineer and do not work in the confines of a case. the 'high air flow' is marketing gimmick to get cheap products to move through the shelves at relatively high margins.
for a low maintenance system, keep two exhaust pressure fans with all the intake ports free of obstructions but with a single layer filter attached. heat extraction is the key to performance. the air will find it's way in, you do not need to go out of your way to get it in your system


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## Vya Domus (Jul 9, 2021)

Ultimately they don't make that much of a difference because once you place a fan over a radiator it will constrict most the air to go one direction anyway, which is through the radiator.


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## Valantar (Jul 9, 2021)

The red spirit said:


> Apparently, CM's static pressure design with long blades is also good at laminar flow. As I understand, turbulent flow is slow flow and in case, disorganization means that it just ends up everywhere, where it shouldn't be, therefore laminar is always preferred. Those two fans are Silencio FP 120 PWM and BladeMaster 120, they don't match in terms of rpms, so for spec comparison I will use blade equivalent MasterFan Pro AP in quiet mode. And for comparison let's add the most generic 7 blade Noiseblocker BlackSilent 120 XL-P:
> rpm 2250 vs 2000 vs 2000
> cfm 53.5 vs 76.8 vs 75.3
> pressure (mmH2O) 3.14 vs 3.90 vs 2.79
> ...


This post clarifies some of the confusion leading to the initial questions here: the lack of clarity in testing methodology when it comes to fan specs.

Firstly, and by far the most importantly: Airflow is measured when _entirely unobstructed_ (in a wind tunnel or similar), while pressure is measured when _fully obstructed_, i.e. at 0 CFM/m3h. These number can _never_ be seen as existing together, but as an either/or pair of extreme (and extremely unlikely in real life) situations. In real life there is always _some_ obstruction, but never total. The question for each fan is how it handles various levels of obstruction and whether it's capable of overcoming it to push air through whatever is obstructing flow, and if so, at what rate. These relationships are highly complex and non-linear (if a fan can produce 100cfm unobstructed and 10 mmH2O when fully obstructed, you don't necessarily get 50cfm at 50% obstruction. This would logically mean that "airflow optimized" in fan design parlance should mean "optimized for maximum airflow at zero or near-zero restriction", while "pressure-optimized" would mean "optimized for maximum pressure when fully or severely impeded" - but it doesn't. The difference they indicate is _far_ smaller than that. See below.

Secondly, and nearly equally importantly: aside from the two highly general points above, there are no accepted industry standards for measuring these things in the PC space. As such, specs between manufacturers are fundamentally incomparable.

Thirdly, no fan manufacturer supplies a full flow+pressure graph for their fans, which would provide a lot more useful information than how it acts at full speed, and could highlight how different blade geometries work differently at different speeds.

Remember, airflow is _extremely _complex, and we can't even really claim to have a complete understanding of all the factors involved from a scientific point of view. Some general principles apply, but the specifics are extremely difficult to ascertain. There's a reason why computational fluid dynamics is a booming field of research, and that findings and methods from this field are widely used on supercomputers and massive computing clusters for designing anything high budget where it might be applicable - aircraft, boats, skyscrapers, and a million different industrial uses.

In the end, airflow is primarily about the transfer of movement energy from a fan motor, through its rotor and blades, to the air. This can obviously be done in many different ways, and is dependent on a host of factors, from blade shape, mass, stiffness/flexibility, speed, size, etc. Server fans create tons of pressure through huge, powerful motors spinning at high speeds, moving thick rotors (i.e. more of a screw shape)  with litte room for back-pressure to push air back out between the blades. Case and cooler fans can't be as thick, so they have to try to balance things somehow.

Airflow optimized fans are designed around minimal flow impedance, and rely on the Bernoulli effect (directed airflow dragging along surrounding atmospheric air in the same direction, increasing flow, as demonstrated here) to maximise flow in unimpeded environments. The Bernoulli effect only applies if no significant backpressure exists, which is why these fans _can_ provide fantastic airflow when unimpeded, but need to be planned around to work. Essentially, for low pressure, high airflow fans to work well, your case needs to be built like a wind tunnel. This is quite unlikely. In reality, most "airflow optimised" fans are instead designed as a middle-of-the-road solution. The Noctua pictured above is a relative rare example of a truly airflow optimized fan - and putting that fan on a restrictive radiator might cause the majority of the air it moves to reflect back off the fins and seep out between the blades, resulting in minimal flow through the rad. But it can also provide a staggering 100m3/h (by Noctua's testing methodology) at just 1200rpm in an unrestricted environment. The fancy new A12x25 needs 2000rpm to achieve the same ariflow - but can produce twice the pressure when fully restricted too. And the low noise optimized 1200rpm version of the NF-A12x25 seems out-and-out worse at just 55,7 m3/h/0.82mmH2O - but its design is likely far better optimized for in-between, partially restricted scenarios. Remember, this is a non-linear relationship. A quiet airflow optimized fan might also turn very noisy if excessively impeded, as the back-pressure from whatever is impeding it will mean that the blades, instead of gently guiding a vortex of airflow, are suddenly chopping through a turbulent mass of air instead.

(Btw, also worth noting from the demonstration video above: in the tests shown, the further the airflow source the faster the bag fills with air, but crucially, only the test with the airflow source clamped to the bag is able to increase pressure in the bag significantly above atmospheric pressure, as in the other cases, once the bag is full, air starts being pushed out as new air is pushed in.)

Pressure optimized fans are designed around, put simply, shoving air forward with a lot of force. Think of moving an oar or paddle through water - if you angle it closer to the direction of desired motion for the boat/canoe, the oar will move more easily through the water, but will impart little movement energy on the boat. Angling the paddle perpendicular to the desired direction of motion makes for a more efficient transfer of energy, making moving the paddle heavier, creating more turbulence in the water, and moving the boat further per stroke, especially at low speeds. Turbulence also causes drag, of course, which is quite inefficient, which is why fan blades aren't designed like flat paddes, but rather to combat drag. But this serves to illustrate why pressure optimized fans typically have more swept blades with a larger visible surface area from either side - they're trying to _shove_ air forward rather than create constant flow. This helps them overcome turbulence and impedance, but also means that the blades chop through the airflow  constantly, slowing down air being dragged in by the flow created on the opposite side, creating more turbulence. Creating a low noise pressure-optimized fan is thus more difficult than a low-noise airflow optimized one, due to the blades creating more and more complex turbulence.

Of course, all of this is grossly oversimplifying the complexities of fluid dynamics. Which blade design is "best" depends on rotational speed, weight, desired/acceptable noise levels, desired/acceptable noise pitch, power restrictions, distance to the impeding element, and a whole host of other factors.

The vast majority of PC fans fall across the rough middle of this spectrum. As someone said above, they aren't air pumps, so truly optimizing for pressure when fully obstructed is nonsensical, and as there will always be _some _restriction, optimizing for airflow at near-zero restriction is also pretty silly. Given the constraints on size (25mm thickness in particular, though some exceed that, like the Arctic P14 at 28, and others at 30+) and power draw, plus the desire for low noise, the resulting designs are typically relatively similar. The vast majority of possible fan designs just aren't suitable for PC use. How manufacturers choose to balance this depends on what they're targeting, their budgets, their price targets, R&D capabilities, etc. - but seeing how fans are a commodity, cheapness tends to dominate. The best performing type of design in situations with moderate-to-high impedance, such as radiators or thick heatsinks, tend to be the "shoving" kind - like the NF-A12x25, Arctic P12/P14, Gentle Typhoon, etc. - but that is also due to most radiators and heatsinks being generally clustered around a middle ground of impedance. Each is built to fit the other, so to speak. And crucially, each is built for _realistic use cases_ rather than zero or full flow impedance.

This, in the end, is why most "airflow optimized" and "pressure optimized" designs are a) rather close within the overall range of possible fan designs, and b) thus perform relatively similarly in most cases. Differences aren't huge simply due to the designs overall not being _that_ different. There are obviously differences, but they are mostly relatively small, and are highly complex in _how_ they are different - noise levels, noise pitch, flow linearity/turbulence, flow patterns, how large the dead spot from the motor is, etc., etc.


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## bug (Jul 9, 2021)

The red spirit said:


> As far as I understand this is the formula of fan airflow:
> air moved = rpms*volume of air that fan blades catch per revolution*static pressure of fan
> 
> It seems that fan static pressure and airflow is very similar to car engine's horsepower, revs and torque. So static pressure in fan is like torque in car and horsepower in car is like airflow in fan. Since fans usually aren't made thicker and most common size of them is 120mm, a hypothetical fan that runs at 1400 rpm, but one is made to be optimized for air flow and other is made to static pressure. That happens if you change blades. However, to achieve higher pressure, some cfm has to be sacrificed, therefore fan is able to provide lower level of air flow, but through more obstructions, meanwhile airflow optimized fan is overall better performing in terms of cfm (and probably in terms of noise, since pressure fans have heavier blades and they vibrate more when spinning), however such fan in theory shouldn't cope well with obstructions. However, from as much as I have observed, a fan blades don't really affect fan performance much. I'm starting to think that higher static pressure fans may have only slightly higher static pressure (makes sense, since a fan isn't a good air pump, due to gaps and due to looking nothing like a proper Archimedes screw) and thus in many practical scenarios higher static pressure just simply fail to deliver any proper advantage over basic airflow optimized fan. Meanwhile air flow fans pretty much always generate enough pressure, so there's no need for any special design. Are these observations true or not?
> ...


Instead of making up formulas, you can just Google: https://techcompass.sanyodenki.com/en/training/cooling/fan_basic/004/index.html


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## Valantar (Jul 9, 2021)

bug said:


> Instead of making up formulas, you can just Google: https://techcompass.sanyodenki.com/en/training/cooling/fan_basic/004/index.html


Wow, that was a great explainer, thanks for sharing!


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## The red spirit (Jul 9, 2021)

Ominence said:


> server fans are mostly pressure based fans so that's what you need. high air flow fans are cheap to engineer and do not work in the confines of a case. the 'high air flow' is marketing gimmick to get cheap products to move through the shelves at relatively high margins.
> for a low maintenance system, keep two exhaust pressure fans with all the intake ports free of obstructions but with a single layer filter attached. heat extraction is the key to performance. the air will find it's way in, you do not need to go out of your way to get it in your system


Or you can just have two static pressure intake fans and two airflow exhaust fans. That way you already have air in your case brought in and then exhausted easily and maybe faster.


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## ThrashZone (Jul 9, 2021)

Hi,
Static fans are usually made a little stronger so they don't bend or get sucked into the closest object that usually being a radiator.... 
Some fans are really cheaply made and flex too much if you try and mount it on the back of a radiator as intake.
Nothing worse than having a fan blade hit a radiator and break lol


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## The red spirit (Jul 9, 2021)

Valantar said:


> Case and cooler fans can't be as thick, so they have to try to balance things somehow.


I don't see any reason why they sometimes couldn't be so. I remember reading that there were 40mm pc fans created, but it was a very niche product, which wasn't advertised much and most people didn't even know that it existed, however, few that have those fans claim that they are great. And for example on tower cooler like 212 Evo, it wouldn't be too difficult to mount 40mm thick fan and it would be possible to have cooler more dense than it already is, so that it performs better. In most cases, you can mount 40mm fans as exhausts too. Intakes are thought due to various obstructions, but I think that 40mm fans certainly could be sold for pc enthusiasts wanting to try something different. And if Corsair, CM or Noctua would release such model, it could gain become a reasonably well known.




Valantar said:


> The vast majority of PC fans fall across the rough middle of this spectrum. As someone said above, they aren't air pumps, so truly optimizing for pressure when fully obstructed is nonsensical, and as there will always be _some _restriction, optimizing for airflow at near-zero restriction is also pretty silly.


lol it was me who said that they are not like Archimedes screw (which I think would be reasonable static pressure fan design, but who knows, if it spins too slow, water can just go back and air would be even harder to start moving. Anyway, since you say that computers will always be restrictive (which is definitely true, even more so for high end systems), wouldn't that mean that you would always want to buy only static pressure optimized fans? Because as you said too, there isn't much from where airflow fan would have unimpeded airflow and thus won't performs nearly as well as they are stated in spec sheet.



ThrashZone said:


> Hi,
> Static fans are usually made a little stronger so they don't bend or get sucked into the closest object that usually being a radiator....
> Some fans are really cheaply made and flex too much if you try and mount it on the back of a radiator as intake.
> Nothing worse than having a fan blade hit a radiator and break lol


I don't think that this should be a major argument for static pressure fans. I never had a fan hitting something and breaking. I have one cheap brittle translucent Cooler Master Blue LED fan and while it may more easily break, it will never bend or start hitting radiators. All my other fans, including generic 7 blade fans, are much stronger and unsurprisingly don't hit anything. I think that you just got very unlucky.


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## Ominence (Jul 9, 2021)

The red spirit said:


> Or you can just have two static pressure intake fans and two airflow exhaust fans. That way you already have air in your case brought in and then exhausted easily and maybe faster.


from a low maintenance perspective, i've to say no to wasting any fans on the intake side. the moment your airway path immediately before or immediately after (filters or grills) the fan blade is restricted, the cfm of HSP will still be higher than that of the so called HAF fans.


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## The red spirit (Jul 9, 2021)

bug said:


> Instead of making up formulas, you can just Google: https://techcompass.sanyodenki.com/en/training/cooling/fan_basic/004/index.html


Thanks a lot for this, it's really good. However, my made up formulae is about calculating fan performance and it isn't about airflow, pressure curve, thus I included how much air fan scoops in each revolution.



Ominence said:


> from a low maintenance perspective, i've to say no to wasting any fans on the intake side. the moment your airway path immediately before or immediately after (filters or grills) the fan blade is restricted, the cfm of HSP will still be higher than that of the so called HAF fans.


It's no for you, but for me it works well. Intake fans help a lot too cool GPU, while keeping system quiet. And dust for me somehow doesn't really accumulate fast, so I never care about minimizing it with fan setup.


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## freeagent (Jul 9, 2021)

I think most consumer grade fans are a joke. SP vs AF? Server fans have both. Common misperception is that they are loud.. yes.. yes they are. But only at full speed. What is SP? It’s just air.. but more of it. Thick fans are where it’s at.


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## bug (Jul 9, 2021)

The red spirit said:


> Thanks a lot for this, it's really good. However, my made up formulae is about calculating fan performance and it isn't about airflow, pressure curve, thus I included how much air fan scoops in each revolution.


It's also wrong. But to hell with the countless engineers that have been working on these for ages, surely they haven't thought about computing airflow volume.


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## claes (Jul 9, 2021)

Great posts @Valantar and @bug 

I’ve been searching through the SPCR archives and ehume’s work to find a concise article, but no luck now that those sites are dead

I do want to add that noctua had been pretty candid about all this. I know they leave a sour taste in a lot of peoples mouth’s, but they have some useful values (check out those PQ curves — they have more docs like this but it’s redundant outside of this piece).





__





						NF-A12x25: interview with Lars Strömbäck (Noctua CTO)
					

Designed in Austria, Noctua's premium cooling components are renowned for their superb quietness, exceptional performance and thoroughgoing quality.




					noctua.at


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## Ominence (Jul 9, 2021)

The red spirit said:


> It's no for you, but for me it works well. Intake fans help a lot too cool GPU, while keeping system quiet. And dust for me somehow doesn't really accumulate fast, so I never care about minimizing it with fan setup.


either you are in a very low dust environment, have no filters on the intake side or your intake fans are doing surprising less than you might imagine.


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## The red spirit (Jul 9, 2021)

bug said:


> It's also wrong. But to hell with the countless engineers that have been working on these for ages, surely they haven't thought about computing airflow volume.


I'm not shitting at engineers, but that formula in Sanyo website is only good for making airflow-static pressure curves. That site also discloses "a typical fan", but what if you increase diameter or thickness? It doesn't account for that.



Ominence said:


> either you are in a very low dust environment, have no filters on the intake side or your intake fans are doing surprising less than you might imagine.


I wouldn't call environment dust free or low dust, but I use two Silencio FP fans at 1080 rpms as intakes. That's not much of airflow, but I don't need much anyway. And from my testing, it seems that increasing intake fan speed has a very direct correlation with GPU temps and fan rpms.


----------



## doyll (Jul 9, 2021)

Computer fan specification are mostly goobledygook.  

Airflow rating is maximum airflow with not restrictions at maximum speed.  Fan test stations have 2 chambers with fan being tested mounted between them.  Each chamber ha it's own fan to balance pressure between chambers.  Some testing is done with fan being tested have equal pressure both intake and exhaust side, a condition a fan in actual use can never have.  Airflow is generated when higher pressure air move into lower pressure are trying to make both equal in pressure.  Our fans draw air from intake side (creating lower pressure area) on intake side and push air out their exhaust side (creating a higher pressure area) on exhaust side.  

So our fan specs are the result of unnatural conditions .. nothing like the conditions when installed on a cooler / radiator or in a case.

But let us say airflow rating is how much air fans can move with no airflow restrictions like grill, filler cables, etc .. like a fan mounted on a stand blowing air in an open room.
And static pressure rating is how much pressure a fan can push into a sealed box.  For the fun of it let's say this fan pushes 1.836 mm H2O of pressure into our box.

1.386 mm H2O static pressure rating, the difference between intake and exhaust sides is extremely low .. so low it's almost impossible to measure.  
The barometric pressure at sea level and 30 feet above sea level is 11.013 mm H20.   
Barometric pressure is the force (pressure) air is pushing against our body.​That is a difference between sea level and 10 feet above sea level of 3.671 mm H2O.   
Which is a difference between sea level and 5 feet above sea level of 1.836 mm H2O 
Few of our fans have 1.836 mm H2O static pressure rating  Most have much lower pressure ratings. 
1.836 mm H2O  pressure rating is the difference in pressure between the air pressure on our feet versus the air pressure on our chest when standing at sea level.


Now let's look at typical airflow resistance in our computer systems.  
Grills lower airflow 29% to 71%.  Open link below and scowl down to see test results.





						SilverStone
					

Founded in 2003, SilverStone is an established leader in its field, with an elite team of engineers; we started our quest of providing products that create inspirations.  We have since expanded the lines of products as well as types of products we produce, giving our customers a wide selection...




					www.silverstonetek.com
				




Filters add even more airflow restriction.
Limited space on intake and exhaust sides of fans also restrict airflow.  
Basic rule of thumb is fans should have their diameter in clearance on both sides.  This means a 120mm fan should have 120mm of free space on intake and exhaust side.
Only vent in most cases with this clearance is rear exhaust and maybe top.
At a bare minimum we should have 1/3rd the diameter  in clearance,  which is 40mm on each side.  
More cases have this kind of clearance.

I could go on and on and on about how specs are at maximum speed and we run our fans at maybe half speed where pressure and airflow ratings are less than have of spec.  But this is already a long post.  

My advice is choose fans with high pressure ratings paying no attention to airflow rating.
Biggest challenge our fans have is overcoming airflow resistance.


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## claes (Jul 9, 2021)

OMG is that @doyll from OCN? Long time no see lol


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## Ominence (Jul 9, 2021)

The red spirit said:


> I wouldn't call environment dust free or low dust, but I use two Silencio FP fans at 1080 rpms as intakes. That's not much of airflow, but I don't need much anyway. And from my testing, it seems that increasing intake fan speed has a very direct correlation with GPU temps and fan rpms.


GPU temps for a given noise level perhaps benefit with intake fans just across them. i like to overcome that issue with brute force exhaust. different approach i guess.



Ominence said:


> i like to overcome that issue with brute force exhaust.


by that i mean my case fans are linked to the GPU temp probe.


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## The red spirit (Jul 9, 2021)

Ominence said:


> GPU temps for a given noise and temp level perhaps benefit with intake fans just across them. i like to overcome that issue with brute force exhaust. different approach i guess.


Well, you can always overcome issues with lots of rpms, but I don't want noise.


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## claes (Jul 9, 2021)

@The red spirit your case (meaning your chassis) is pretty unique/totally normal in this regard, in that it’s not representative of most fan test environments. It makes a lot of sense that negative pressure would work out well for you — might even consider removing your PCI brackets for fun


----------



## Ominence (Jul 9, 2021)

The red spirit said:


> Well, you can always overcome issues with lots of rpms, but I don't want noise.


with 15000rpms of case fans mine is an absolute jet at cold post. very quite from there on depending on the fan curve. 20% duty cycle at idle or 3000rpms combined. my aircon is louder than the pc.


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## Valantar (Jul 9, 2021)

The red spirit said:


> I don't see any reason why they sometimes couldn't be so. I remember reading that there were 40mm pc fans created, but it was a very niche product, which wasn't advertised much and most people didn't even know that it existed, however, few that have those fans claim that they are great. And for example on tower cooler like 212 Evo, it wouldn't be too difficult to mount 40mm thick fan and it would be possible to have cooler more dense than it already is, so that it performs better. In most cases, you can mount 40mm fans as exhausts too. Intakes are thought due to various obstructions, but I think that 40mm fans certainly could be sold for pc enthusiasts wanting to try something different. And if Corsair, CM or Noctua would release such model, it could gain become a reasonably well known.


They can't be thicker than 25mm without breaking the (de facto? I have no idea if this is official in any way) standard for PC case and cooler fans, risking severe compatibility issues. There are many places where a >25mm fan can fit, but that doesn't mean that producing such a fan would be unproblematic. With all else being equal, the return rate for a thicker fan due to it not fitting the intended use would be higher simply due to it being thicker than standard.

Of course designing a thicker fan for consumer use is also problematic in that no such fans exist, and adapting a server or industrial design is likely to be difficult (different factors to consider). In other words: it would be expensive. And as I said, fans are a commodity, and costs matter.

Then there's the actual benefits: unless you are running a _very_ thick and restrictive radiator, current 25mm fan designs perform pretty well, and significantly beating that without getting to the range where two 25mm fans in push-pull would be an alternative is very difficult, especially at low noise levels. And as pressure stacks with fans in series, two fans of X mmH2O = 2X mmH2O (minus some interference losses). Thus, a 40mm+ fan would need to outperform not one, but two 25mm fans stacked, while still staying at a reasonable development cost.

There are some thicker fans out there, like EK's 38mm Meltemi fans, though those only really outperform 25mm fans in specific scenarios (in particular: restrictive rads in pull configuration).


The red spirit said:


> lol it was me who said that they are not like Archimedes screw (which I think would be reasonable static pressure fan design, but who knows, if it spins too slow, water can just go back and air would be even harder to start moving. Anyway, since you say that computers will always be restrictive (which is definitely true, even more so for high end systems), wouldn't that mean that you would always want to buy only static pressure optimized fans? Because as you said too, there isn't much from where airflow fan would have unimpeded airflow and thus won't performs nearly as well as they are stated in spec sheet.


As you say, an archimedes screw would be a pretty terrible air pump though - you need something that seals, i.e. a piston mechanism or similar for that. But you seem not to have read very carefully: I also point out that _all_ PC fan designs fall along a relatively narrow spectrum of possible designs. This means that most "airflow optimised" fans _still_ produce a modicum of static pressure when restricted, and that most "pressure optimized" fans still provide good airflow when unrestricted. So while there _are_ differences, they are small and nuanced. If your case is extremely unrestrictive and has a good airflow layout with equal intake and exhaust, a good set of airflow optimized fans will likely provide more airflow through the case at the same noise level as a set of good pressure optimized fans. But you'd still want a _more_ pressure-optimized fan attached to any heatsinks in the case, as airflow will otherwise choose the path of least resistance and any airflow-optimized fans mounted to these will perform somewhat worse. Not a world of difference, but some (as long as all fans are assumed to be good designs). But if, for example, your case has less affordances for air to leave the case than enter it (forcing a positive pressure setup), then yes, you want fans better optimized for pressure, as you'd otherwise risk losing effective airflow due to back-pressure. Again, the difference isn't likely to be major, but it would be measurable.

Edit: in a case like yours, which is highly restrictive by design, airflow will always be hampered regardless of your choice of fan, but good "pressure optimized" fans are still likely to perform better than "airflow optimized" ones.


----------



## Ominence (Jul 9, 2021)

Valantar said:


> They can't be thicker than 25mm without breaking the (de facto? I have no idea if this is official in any way) standard for PC case and cooler fans, risking severe compatibility issues. There are many places where a >25mm fan can fit, but that doesn't mean that producing such a fan would be unproblematic. With all else being equal, the return rate for a thicker fan due to it not fitting the intended use would be higher simply due to it being thicker than standard.


how does a 125mm stacker 15000rpm 'sound' with my setup. 160mm and 18000 peak rpm if you include the cpu fan blowing very close in the same direction, and the single case grill in the middle. i have a stupid setup, thought it nice to give people a good laugh and cringe for others.


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## Valantar (Jul 9, 2021)

Ominence said:


> from a low maintenance perspective, i've to say no to wasting any fans on the intake side. the moment your airway path immediately before or immediately after (filters or grills) the fan blade is restricted, the cfm of HSP will still be higher than that of the so called HAF fans.


You have no intake fans at all? That's a balancing act, and highly dependent on the case. The (negative) pressure produced by the exhaust fans then have to work on a much larger area (every available opening in the case), so depending on the size of the case and how restrictive it is, as well as how well positioned these air intakes are to components in need of fresh air, it can either be really great or downright terrible. A lot of sandwich layout SFF cases with radiator support perform _drastically_ better with all fans set as exhaust, pulling fresh air in through ventilated side panels. But in other cases the fresh air might bypass the components in need of cooling entirely - it depends where it can get in more easily, and as pressure will decrease in the case the further from the fan you are (unless your case is a near-perfect wind tunnel with equal active exhausts and passive intakes), air will be more likely to enter closer to the fan if it is able to.


Ominence said:


> how does a 125mm stacker 15000rpm 'sound' with my setup. 160mm and 18000 peak rpm if you include the cpu fan blowing very close in the same direction, and the single case grill in the middle. i have a stupid setup, thought it nice to give people a good laugh and cringe for others.


15000 rpm? Unless you're running some sort of high speed server fans, you can't add up rpms. Stacked fans add pressure, not airflow (except when said pressure serves to overcome a restriction, which is always up to a cut-off point), and rpm is effectively the same no matter the amount of fans. Of course stacked (serial) and side-by-side (parallel) fans affect airflow in a system in very different ways - side-by-side fans _do_ add up in airflow, but not really in pressure (that Sanyo link on the previous page illustrates this nicely). Parallel fans increase swept area, stacked fans increase pressure.


----------



## The red spirit (Jul 9, 2021)

claes said:


> @The red spirit your case (meaning your chassis) is pretty unique/totally normal in this regard, in that it’s not representative of most fan test environments. It makes a lot of sense that negative pressure would work out well for you — might even consider removing your PCI brackets for fun


How it is even a bit unique? I only have Silencio S400, a small case, packed with lots of impedances. It's pretty much looks like any other generic mATX modern silent case. Define C Mini should perform similarly to this S400. Anyway, I have two stock fans (Silencio FP 120mm) set at 1080 rpm as two from intakes and due to DVD drive restriction, I use two exhaust fans, which are both Silverstone Globe 120mm rpms fans (from Grandia GD05B), one is rear exhaust and other is rear top exhaust. They both run at less 650-680 rpms. That's slow, but I noticed that they get a lot noisier than Silencio FPs at same rpms and so my current setup is setup more for minimal noise, rather than ideal thermal performance. There thermal performance of my machine is satisfactory, meaning it's quiet enough so I don't care and cool enough, so it stays quiet enough and safe enough. If I cared more about airflow, I would replace Globe fans with same Silencio FPs as they seem to be exceptionally quiet at quite a bit more rpm. But since I don't have any particularly hot hardware, there's not much reason for me to mess with fan setup. In fact I could remove two fan and just use those two Silencios only, but then my graphics card runs louder and I don't like that. With current setup graphics card runs Unigine Heaven benchmark and stays at around 1300 rpm. And I tolerate only under 1500 rpm. And now are one of the hottest summer days too. 

And it would seem that I have positive pressure setup, but that's most likely not a case either. Those Silencio FPs have high pressure rating and a lot lower cfm rating, so they probably in real life also push less real cfms too and those two Silverstone Globe's at less than 700 rpm likely match them in terms of airflow, since their only restrictions are case grille an top fan filter. In terms of dust, I have been using this case for like 3 months and front filter is a bit dusty. Case is a bit dusty, but heatsinks are pretty much perfectly clean. Only PSU filter had some serious dust, but that's it. I don't remember having system this decently clean in Cooler Master K280 case, so S400 is an improvement.


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## Valantar (Jul 9, 2021)

The red spirit said:


> And it would seem that I have positive pressure setup, but that's most likely not a case either. Those Silencio FPs have high pressure rating and a lot lower cfm rating, so they probably in real life also push less real cfms too and those two Silverstone Globe's at less than 700 rpm likely match them in terms of airflow, since their only restrictions are case grille an top fan filter.


Remember that your front fans are severely impeded by the solid front panel and the narrow front-side air intakes. Airflow loses ~50% of its pressure over a 90° turn, and there's a filter there too, so they are likely quite restricted. Unless you're noticing dust ingress along case seams and cracks you're likely at rough equilibrium or slight positive pressure though.


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## The red spirit (Jul 9, 2021)

Valantar said:


> They can't be thicker than 25mm without breaking the (de facto? I have no idea if this is official in any way) standard for PC case and cooler fans, risking severe compatibility issues. There are many places where a >25mm fan can fit, but that doesn't mean that producing such a fan would be unproblematic. With all else being equal, the return rate for a thicker fan due to it not fitting the intended use would be higher simply due to it being thicker than standard.


Well, that's marketing's job to inform user that these are thicc bois and that you can't just simply buy and mount them anywhere. Seems pretty easy to to pull off. But if you are paranoid, you can just ship them with CPU cooler, so that people would pay attention to dimensions.



Valantar said:


> Of course designing a thicker fan for consumer use is also problematic in that no such fans exist, and adapting a server or industrial design is likely to be difficult (different factors to consider). In other words: it would be expensive. And as I said, fans are a commodity, and costs matter.


Still, I see no reason why computer luxury brands like Corsair or Noctua couldn't experiment with that. Their buyers aren't always geniuses and they sure are willing to buy some poor value products, because Noctua, because Corsair. And I said that somebody already made those and sold them. I really can't recall who, but it may be Delta or other OEM, who specialize mostly in servers.




Valantar said:


> I also point out that _all_ PC fan designs fall along a relatively narrow spectrum of possible designs. This means that most "airflow optimised" fans _still_ produce a modicum of static pressure when restricted, and that most "pressure optimized" fans still provide good airflow when unrestricted. So while there _are_ differences, they are small and nuanced.


So it's a better idea to err on static pressure side, if you have no idea how restrictive your case insides and grilles are?




Valantar said:


> Edit: in a case like yours, which is highly restrictive by design, airflow will always be hampered regardless of your choice of fan, but good "pressure optimized" fans are still likely to perform better than "airflow optimized" ones.


That's why it came with two Silencio FP fans.


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## Ominence (Jul 9, 2021)

Valantar said:


> You have no intake fans at all? That's a balancing act, and highly dependent on the case. The (negative) pressure produced by the exhaust fans then have to work on a much larger area (every available opening in the case), so depending on the size of the case and how restrictive it is, as well as how well positioned these air intakes are to components in need of fresh air, it can either be really great or downright terrible. A lot of sandwich layout SFF cases with radiator support perform _drastically_ better with all fans set as exhaust, pulling fresh air in through ventilated side panels. But in other cases the fresh air might bypass the components in need of cooling entirely - it depends where it can get in more easily, and as pressure will decrease in the case the further from the fan you are (unless your case is a near-perfect wind tunnel with equal active exhausts and passive intakes), air will be more likely to enter closer to the fan if it is able to.


yup, no intakes- all unobstructed openings with the stock fan filters everywhere else. FDDR6 case- no front door or top closed panel and with all exhaust fans on the back fan location. the 2nd cpu fan is the turbulence generator for a lot of fun airpaths within the case. that 2nd fan blows towards the front of the case! and i guess the psu fan must do a little too with the fan facing up and exhausting out the back as well.


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## The red spirit (Jul 9, 2021)

Valantar said:


> Remember that your front fans are severely impeded by the solid front panel and the narrow front-side air intakes. Airflow loses ~50% of its pressure over a 90° turn, and there's a filter there too, so they are likely quite restricted. Unless you're noticing dust ingress along case seams and cracks you're likely at rough equilibrium or slight positive pressure though.


I'm not so sure about exactly losing a lot of pressure, because opening doors does surprisingly next to nothing. As for grille, it really doesn't look very restrictive. So in reality, I probably don't lose much pressure. Still, Silencio FPs from hand measurement don't provide much airflow so even without pressure loss, in my case there's probably only a tiny bit positive pressure or neutral pressure.


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## Ominence (Jul 9, 2021)

Valantar said:


> 15000 rpm? Unless you're running some sort of high speed server fans, you can't add up rpms. Stacked fans add pressure, not airflow (except when said pressure serves to overcome a restriction, which is always up to a cut-off point), and rpm is effectively the same no matter the amount of fans. Of course stacked (serial) and side-by-side (parallel) fans affect airflow in a system in very different ways - side-by-side fans _do_ add up in airflow, but not really in pressure (that Sanyo link on the previous page illustrates this nicely). Parallel fans increase swept area, stacked fans increase pressure.


i'm kidding- that's 5x3000 stacked together. i don't think noobs will be too interested in this thread so surely no one should really believe it, like you didn't! i do not intend any misdirection- just fun participation. i would love to do an rpm test one day on the last serial fan in the stack. that should be doing some 'fun' rpms regardless of the 3k rated speed. force fed induction is great.


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## 80251 (Jul 9, 2021)

freeagent said:


> I think most consumer grade fans are a joke. SP vs AF? Server fans have both. Common misperception is that they are loud.. yes.. yes they are. But only at full speed. What is SP? It’s just air.. but more of it. Thick fans are where it’s at.


There are some amazingly thick and powerful fans made by Delta, Nidec and SanAce. Most of them are vaneaxials, some of them are contra-rotating dual fan assemblies. The amount of static pressure and CFM these fans put out makes anything by noctua look like a joke.


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## qubit (Jul 9, 2021)

Static pressure = pressure. Just a different term for the same thing.


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## The red spirit (Jul 9, 2021)

80251 said:


> There are some amazingly thick and powerful fans made by Delta, Nidec and SanAce. Most of them are vaneaxials, some of them are contra-rotating dual fan assemblies. The amount of static pressure and CFM these fans put out makes anything by noctua look like a joke.


Joke? Sorry mate, look at specs. Here is Noctua NF-A12x25 vs Delta AFB1212L-R00:
rpm 2000 vs 1900
cfm 60.09 vs 62.93
mmH2O 2.34 vs 3.93
dBA 22.6 vs 32.5
MTTF 150k vs 70k

While air moving specs are great, Delta fan is a total disaster in terms of noise. Also Delta fan may or may not last shorter. Meanwhile, Noctua's Industrial NF-F12 is better than Delta at every single measure. It moves more air, it has more pressure, it lasts longer is quieter and consumes less power. 

And what you could have expected, Delta just makes generic 7 bladers, doesn't give any dampening rubber, uses ball bearing. It's surprising that it wasn't beaten any worse than it already is.

Nidec doesn't even make anything that doesn't rape your ears and something that doesn't set motherboards fan connector on fire. And they sell some crazy stuff. 9800 rpm fan? They make that:








						V12C-M3 | Nidec Corporation
					






					www.nidec.com
				



They also don't disclose what connector their fans have.

Sanyo Denkis are also no match for Noctua Industrials and on top of that they fail to deliver as much pressure as 7 blader Delta. So they are boring too. And they don't make any crazy near 10k rpm fans either, super boring. And yet they still burn motherboards.


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## 80251 (Jul 9, 2021)

Wow the ignorance of the type of fans Delta, SanAce and Nidec manufacture is remarkable. Delta, Nidec and SanAce are renowned for their longevity because they're designed to work in server environments -- 24-7-365. I've never come across anyone working in any datacenter who uses any Noctua fans whatsoever -- because they're far too weak. No server manufacturer uses Noctua fans either.
Noctua makes very few fans that have more than 100CFM. Why don't you compare fans that produce > 100 CFM? Noctua doesn't even have ANY fans that produce > 150CFM and I don't trust the specs on their NF-A14 iPPC-3000.


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## Valantar (Jul 9, 2021)

The red spirit said:


> Well, that's marketing's job to inform user that these are thicc bois and that you can't just simply buy and mount them anywhere. Seems pretty easy to to pull off. But if you are paranoid, you can just ship them with CPU cooler, so that people would pay attention to dimensions.


You can't inform consumers out of assuming a product that breaks an ubiquitous standard is standard-compliant. Most buyers don't look that closely. There will always be a higher return rate for a product like this, and marketing can't do anything to fix that.


The red spirit said:


> Still, I see no reason why computer luxury brands like Corsair or Noctua couldn't experiment with that. Their buyers aren't always geniuses and they sure are willing to buy some poor value products, because Noctua, because Corsair. And I said that somebody already made those and sold them. I really can't recall who, but it may be Delta or other OEM, who specialize mostly in servers.


They have no doubt done the research and concluded that it's not worth it. For heatsinks, a thicker fan means less fin area for the largest ones - space in a case is finite, after all - where the better fan would be of the most benefit. And a thinner fin stack is less restrictive, meaning the thicker fan would lose its main benefit. For case fans, you can't generally assume that all cases are wide open around their fan mounts. And again, it might not provide a sufficient benefit to actual airflow without sacrificing other metrics. Also, I think you're being a bit too optimistic about how easy it is to amortize the R&D cost of a brand new, non-standard fan design across sales, especially when sales will be lower due to compatibility issues.

Also, I mentioned one of the more available thicker options above, the EK Meltemi 38mm. It's not particularly good - it outperforms the 25mm Vardar on thick radiators in pull configurations, but that's about it. In push or with a thinner radiator it's no better.


The red spirit said:


> So it's a better idea to err on static pressure side, if you have no idea how restrictive your case insides and grilles are?


Yep, pretty much. But as I said, differences between well designed fans are relatively small, and most "AF" fans are much closer to SP fans than actual AF fan designs.


Ominence said:


> i'm kidding- that's 5x3000 stacked together. i don't think noobs will be too interested in this thread so surely no one should really believe it, like you didn't! i do not intend any misdirection- just fun participation. i would love to do an rpm test one day on the last serial fan in the stack. that should be doing some 'fun' rpms regardless of the 3k rated speed. force fed induction is great.


Sheesh, that sounds ... interesting  I kind of doubt that last fan will be spinning much over spec though - stacking fans only increases pressure and serves to overcome restriction, flow stays the same (or might even drop due to turbulence between the rotors). It will likely be spinning faster than if it was alone simply due to more pressure allowing it to operate with less restriction, but the difference won't be huge.



80251 said:


> Wow the ignorance of the type of fans Delta, SanAce and Nidec manufacture is remarkable. Delta, Nidec and SanAce are renowned for their longevity because they're designed to work in server environments -- 24-7-365. I've never come across anyone working in any datacenter who uses any Noctua fans whatsoever -- because they're far too weak. No server manufacturer uses Noctua fans either.
> Noctua makes very few fans that have more than 100CFM. Why don't you compare fans that produce > 100 CFM? Noctua doesn't even have ANY fans that produce > 150CFM and I don't trust the specs on their NF-A14 iPPC-3000.


Noctua doesn't target servers, as their niche is silence, and nobody cares about silence in a server. So ... yeah. That point is kind of moot. You're not getting a silent > 150CFM 120mm fan either, no matter what you do. As for reliability, I've never heard of Noctuas not handling 24/7 running (what's with people operating with 365-week years? Mine only have 52.), but obviously they're not 10 000rpm server screamers, and couldn't handle those kinds of loads. They aren't made for that. Different tools for different purposes.

Also, most server fans have dual ball bearings, which makes them grindy and noisy at low to medium RPMs. Just ask any Gentle Typhoon owner who has since experienced a good non-ball-bearing fan. The difference is very noticeable.


----------



## The red spirit (Jul 9, 2021)

80251 said:


> Wow the ignorance of the type of fans Delta, SanAce and Nidec manufacture is remarkable. Delta, Nidec and SanAce are renowned for their longevity because they're designed to work in server environments -- 24-7-365. I've never come across anyone working in any datacenter who uses any Noctua fans whatsoever -- because they're far too weak. No server manufacturer uses Noctua fans either.


I'm pretty sure that they just don't wanna pay for luxury fans. 



80251 said:


> Noctua makes very few fans that have more than 100CFM. Why don't you compare fans that produce > 100 CFM? Noctua doesn't even have ANY fans that produce > 150CFM and I don't trust the specs on their NF-A14 iPPC-3000.


Because those high CFM fans spin at crazy rpms and are loud, if not outright burning every motherboards' fan connectors. You know, they have maximum power ratings too and they surely aren't made to handle 20+ watt fans.



Valantar said:


> You can't inform consumers out of assuming a product that breaks an ubiquitous standard is standard-compliant. Most buyers don't look that closely. There will always be a higher return rate for a product like this, and marketing can't do anything to fix that.


I doubt that. I meant the whole mITX market exists and they are are always thinking of ways to makes computers smaller and people buy that stuff.



Valantar said:


> For case fans, you can't generally assume that all cases are wide open around their fan mounts.


I clearly mentioned that thicker fans would be for those that do their own research and I don't expect them to fit everywhere. 




Valantar said:


> Also, I think you're being a bit too optimistic about how easy it is to amortize the R&D cost of a brand new, non-standard fan design across sales, especially when sales will be lower due to compatibility issues.


How hard could it possibly be. Just give review units to LTT, JayZ, Bitwit and write in big bold letters, that these fan's won't fit everywhere. Done. And write that on your website and fan box. Now, truly done. You know, it's not like we didn't have 200mm fans or even bigger 240mm fans in computers. 




Valantar said:


> Also, I mentioned one of the more available thicker options above, the EK Meltemi 38mm. It's not particularly good - it outperforms the 25mm Vardar on thick radiators in pull configurations, but that's about it. In push or with a thinner radiator it's no better.


That's because it's a pressure design, give that extra thickness to airflow design and it may do wonders.


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## DeathtoGnomes (Jul 9, 2021)

Valantar said:


> Different tools for different purposes.


This pretty well sums up a lot., the right fan for the right job. 

Appreciate this entire discussion on fans, and vote to put in the hall of fame .


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## MentalAcetylide (Jul 10, 2021)

Ominence said:


> how does a 125mm stacker 15000rpm 'sound' with my setup. 160mm and 18000 peak rpm if you include the cpu fan blowing very close in the same direction, and the single case grill in the middle. i have a stupid setup, thought it nice to give people a good laugh and cringe for others.


Does anyone even make 120/140mm PC case fans capable of reaching those speeds or is this a ghetto-type mod? 
I can only imagine how loud it would be having 4-5 of them in a PC case spinning at 10,000+rpm. With fans like that, why even bother putting them inside the case when you can install them down in the basement & pipe the freakin cool air right into the case.  For that amount of trouble, might as well hire an HVAC specialist to install a separate AC unit for the case and just have a 1-2 fans blowing out the warmer air...


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## The red spirit (Jul 10, 2021)

MentalAcetylide said:


> Does anyone even make 120/140mm PC case fans capable of reaching those speeds or is this a ghetto-type mod?
> I can only imagine how loud it would be having 4-5 of them in a PC case spinning at 10,000+rpm. With fans like that, why even bother putting them inside the case when you can install them down in the basement & pipe the freakin cool air right into the case.  For that amount of trouble, might as well hire an HVAC specialist to install a separate AC unit for the case and just have a 1-2 fans blowing out the warmer air...


Not to mention that fans at such rpms heat up a lot themselves and consume a lot of power.


----------



## claes (Jul 10, 2021)

The red spirit said:


> How it is even a bit unique? I only have Silencio S400, a small case, packed with lots of impedances. It's pretty much looks like any other generic mATX modern silent case. Define C Mini should perform similarly to this S400. Anyway, I have two stock fans (Silencio FP 120mm) set at 1080 rpm as two from intakes and due to DVD drive restriction, I use two exhaust fans, which are both Silverstone Globe 120mm rpms fans (from Grandia GD05B), one is rear exhaust and other is rear top exhaust. They both run at less 650-680 rpms. That's slow, but I noticed that they get a lot noisier than Silencio FPs at same rpms and so my current setup is setup more for minimal noise, rather than ideal thermal performance. There thermal performance of my machine is satisfactory, meaning it's quiet enough so I don't care and cool enough, so it stays quiet enough and safe enough. If I cared more about airflow, I would replace Globe fans with same Silencio FPs as they seem to be exceptionally quiet at quite a bit more rpm. But since I don't have any particularly hot hardware, there's not much reason for me to mess with fan setup. In fact I could remove two fan and just use those two Silencios only, but then my graphics card runs louder and I don't like that. With current setup graphics card runs Unigine Heaven benchmark and stays at around 1300 rpm. And I tolerate only under 1500 rpm. And now are one of the hottest summer days too.
> 
> And it would seem that I have positive pressure setup, but that's most likely not a case either. Those Silencio FPs have high pressure rating and a lot lower cfm rating, so they probably in real life also push less real cfms too and those two Silverstone Globe's at less than 700 rpm likely match them in terms of airflow, since their only restrictions are case grille an top fan filter. In terms of dust, I have been using this case for like 3 months and front filter is a bit dusty. Case is a bit dusty, but heatsinks are pretty much perfectly clean. Only PSU filter had some serious dust, but that's it. I don't remember having system this decently clean in Cooler Master K280 case, so S400 is an improvement.


That’s why I said “unique/totally normal”  Ots a common case design but not the sort of environment used for testing fans

And a little nudge again — try removing pci brackets to further reduce GPU noise. You may even be able to remove one set of fans after that mod


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## Shrek (Jul 10, 2021)

The red spirit said:


> Eh, bearing life span barely matters in reality. It's not that it doesn't matter, but because even very basic and cheap sleeve fans survive for more than decade and their lifespan could be extended with re-oiling them and keeping them clean. Pretty much anything more than sleeve fan is overkill.


Not so sure, capacitors and fans seem to be the first thing to wear out for power supplies and one must catch a dry fan early for reoiling or the supply will overheat.

That said, I tend to recap what I have with top quality replacements and oil the fans with a lot more oil than they had originally; at that point I'd tend to agree with you.


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## Mescalamba (Jul 10, 2021)

Its not a scam and you need static pressure fans pretty much only in case you have high fin count radiator or some really densely packed air cooler over CPU.

For regular air cooling (air in case, air out of case) it doesnt matter much apart those odd designs that give only tiny amount of intake/output space so you need high pressure fan to actually get some air in it or out (problem is usually getting it in).

I think manufacturers focus on other stuff too simply cause not all users are that demanding (as for example ones using liquid cooling custom loops) and also it does have impact on sound (moving a lot of air quick and with pressure does make some noise, its impossible to avoid). Its reason for batwings and similar stuff that lowers sound when rotor moves fast. Usually minimal impact on air pressure.

As for design to air pressure, well look at jet engine turbine vs rotor propelled airplane. Solution is rather clearly "more lamels + higher RPM = more pressure". 

Fairly sure even dual-blades fan could generate enough pressure, if those blades are big/curved enough and RPM is high too. Could be actually interesting experiment, if it has any positive impact on sound or not.


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## Shrek (Jul 10, 2021)

I believe the less blades on a propeller the more efficient.


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## claes (Jul 10, 2021)

Mescalamba said:


> Its not a scam and you need static pressure fans pretty much only in case you have high fin count radiator or some really densely packed air cooler over CPU.
> 
> For regular air cooling (air in case, air out of case) it doesnt matter much apart those odd designs that give only tiny amount of intake/output space so you need high pressure fan to actually get some air in it or out (problem is usually getting it in).


I don’t think that’s true at all... Even in “airflow” cases you still have a high-impedance filter to overcome. If you look at GN’s reviews those cases often drop 10* just by removing the filter. Filters are much more restrictive than the hex cutouts you often see in the exhaust positions. Nevermind that the majority of cases ship with a solid front panel and tiny side vents in addition to a filter.

IMO, exhaust is the only time airflow fans make more sense than a well-optimized/static pressure oriented fan. Exhaust is the only real situation where direction matters (well, maybe also if you’re using a blower GPU, but the intake problem mitigates this IMO) and, unless your intake is open air, you’re always going to have to overcome a lot of impedance with pressure.


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## freeagent (Jul 10, 2021)

To be fair my iPPC fans have to rev to 3K to match the 110 CFM rating of my 2500rpm Panaflos, not counting the pressure yet.

And my TY-143 only needed 2500rpm for 130cfm.


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## Ominence (Jul 10, 2021)

Valantar said:


> It will likely be spinning faster than if it was alone simply due to more pressure allowing it to operate with less restriction, but the difference won't be huge.


given the noise it makes at full chat, I'm sure that rpm is a factor other than mere pressure impedance differences. and it is more cfm without doubt. diminishing returns perhaps of course, but more for sure. i am sure people in this thread have heard high speed drone motors running at different speeds and how their sound signature changes at those rpms.



MentalAcetylide said:


> Does anyone even make 120/140mm PC case fans capable of reaching those speeds or is this a ghetto-type mod?
> I can only imagine how loud it would be having 4-5 of them in a PC case spinning at 10,000+rpm. With fans like that, why even bother putting them inside the case when you can install them down in the basement & pipe the freakin cool air right into the case.  For that amount of trouble, might as well hire an HVAC specialist to install a separate AC unit for the case and just have a 1-2 fans blowing out the warmer air...


that is a so called ghetto setup but you may have missed me mentioning later that they are a stacked setup of 5 fans @ 3k rpms each and 125mm thick (so no, not 10k+ rpms in fact) . it idles quieter at 20% duty cycle than my aircon.


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## FireFox (Jul 10, 2021)

Because we're talking about fans i have a question: if my fans are rated 1500rpm but i make them run at 1600rpm what could it happens to it?


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## 80251 (Jul 10, 2021)

Andy Shiekh said:


> I believe the less blades on a propeller the more efficient.


It depends on what you mean by efficient. Prop-driven fighters in WW2 started out with three-bladed propellers, but by the end of the war the piston engines became so powerful they needed 4-bladed propellers with gigantic paddle blades to harness all that horsepower and torque and the improvement in performance was noticeable for the P-51d mustang and P-47d Thunderbolt.

Three-bladed fans never produce much static pressure -- even at high RPM's.


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## Ominence (Jul 10, 2021)

FireFox said:


> Because we're talking about fans i have a question: if my fans are rated 1500rpm but i make them run at 1600rpm what could it happens to it?


you want the alarmist version?- then fan hub failure- demagnetisation! however i expect your fan to have the usual 10% tolerance meaning 1350 to 1650 operating range.


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## Shrek (Jul 10, 2021)

80251 said:


> It depends on what you mean by efficient.


Fuel per mile


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## Ominence (Jul 10, 2021)

Andy Shiekh said:


> I believe the less blades on a propeller the more efficient.


twin blade prop vs jet turbine for efficiency....any fluid dynamicists here?? i do realise that jets do not directly create airflow over the wings.



Andy Shiekh said:


> Fuel per mile


probably should be fuel per thrust unit, of the blade and drive unit, or something similar.


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## Space Lynx (Jul 10, 2021)

my two cents is that they are not a scam. I noticed excellent airflow improvement when I changed my stock PC case exhaust fan to the NZXT Aer-P fan. it just pushes air through the exhaust metal grill better cause of the 'airplane' like fan blades it has.

excellent fan, probably the best fan I have ever bought. I like it more than my Noctua fans.


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## Ominence (Jul 10, 2021)

lynx29 said:


> noticed excellent airflow improvement when I changed my stock PC case exhaust fan


that's not a high bar to overcome mate in the absolute vast majority of cases. any decent AF fan can outperform a stock case fan.


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## Space Lynx (Jul 10, 2021)

Ominence said:


> that's not a high bar to overcome mate in the absolute vast majority of cases. any decent AF fan can outperform a stock case fan.



true but something about it I just like. I like the design of it, feels high quality, etc.


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## 80251 (Jul 10, 2021)

MentalAcetylide said:


> Does anyone even make 120/140mm PC case fans capable of reaching those speeds or is this a ghetto-type mod?
> I can only imagine how loud it would be having 4-5 of them in a PC case spinning at 10,000+rpm. With fans like that, why even bother putting them inside the case when you can install them down in the basement & pipe the freakin cool air right into the case.  For that amount of trouble, might as well hire an HVAC specialist to install a separate AC unit for the case and just have a 1-2 fans blowing out the warmer air...



10,000 RPM fans, yeah that's all Delta, SanAce and Nidec make. Maybe you should look at their product catalogs sometime and realize they manufacture all kinds of fans and blowers -- some of which don't even run at 12V.


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## Ominence (Jul 10, 2021)

lynx29 said:


> to the NZXT Aer-P fan.


I just checked and it's a pressure optimised design so well done, a good choice. as a still proud owner of an original NZXT Phantom red case on one of my other systems, hopefully NZXT have decided to go with better suppliers for their fans than in those early days! their 200mm fans were trash.


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## Valantar (Jul 10, 2021)

Andy Shiekh said:


> Fuel per mile


Lower rotating mass will inevitably lead to higher efficiency, but only if it can maintain sufficient energy transfer with that lower mass. There's always a balance. Of course with fewer blades, literal balancing of the rotor is also a crucial problem that needs solving.


FireFox said:


> Because we're talking about fans i have a question: if my fans are rated 1500rpm but i make them run at 1600rpm what could it happens to it?


Likely not much. As @Ominence mentioned, fans are typically rated at +/- 10% rotational speed, so if rated at 1500rpm it might top out at anywhere from 1350 to 1650rpm. Of course if it tops out at 1500rpm actual rotation speed at the rated voltage and 100% PWM and you have to overvolt them to run them faster, that might cause the motor to wear out faster. Likely not much from such a small change though. A fan rated at 12V operation can often handle much higher (15-16V at least) for short periods, so a low overvoltage over time is likely entirely within its tolerances.


The red spirit said:


> I doubt that. I meant the whole mITX market exists and they are are always thinking of ways to makes computers smaller and people buy that stuff.


Hm? I don't see how that's relevant. mITX is a standard. Heck, if anything, the SFF PC market is an excellent demonstration of how breaking standards leads to problems - try to google how many people have issues fitting the DTX Asus Crosshair 8 Impact into various SFF ITX cases, for example. SFF cases also tendt to be _very_ meticulous in documenting their clearances and limitations for non- or not-quite standardized things like radiator/fan fitment (not the size or mounting patterns, but if any can fit, how large, etc.), CPU cooler clearances, GPU size, etc. As for trying to make PCs smaller, the whole point is doing so _while maintaining compatibility_. Look at the Dan A4 for example - the entire purpose of that case is allowing you to build a powerful PC with all standard components - ITX motherboard, dual-slot full-size GPU, SFX PSU. All accepted standards. There are plenty of proprietary SFF solutions from the likes of Zotac, but you can't build those yourself. DIY requires adherence to standards to work.


The red spirit said:


> I clearly mentioned that thicker fans would be for those that do their own research and I don't expect them to fit everywhere.


But you're not accepting the inherent consequences of that, in (likely much) lower sales and limited compatibility. Of PC gamers (to pick a sizeable group with high performance PCs), only a small minority DIY build their PCs. Of those, only a small minority buy additional fans beyond those that come with their case. Of those, a large portion likely just buy whatever is cheapest as they discover free fan slots and are given advice online to just stuff it full of fans. So the people doing targeted purchases of brand-name fans? That's already a very small group. Adding "use cases where a thicker fan will fit and provide tangible benefit" is likely to make the target market so small as to be near meaningless. Meaning that with any significant R&D cost, these fans would become _ridiculously _expensive. High end 25mm fans like the NF-A12x25 are already ridiculously expensive. Starting from scratch with literally every single part of the fan for a >35mm fan? I wouldn't be surprised if that doubled the costs from there.


The red spirit said:


> How hard could it possibly be. Just give review units to LTT, JayZ, Bitwit and write in big bold letters, that these fan's won't fit everywhere. Done. And write that on your website and fan box. Now, truly done. You know, it's not like we didn't have 200mm fans or even bigger 240mm fans in computers.


You clearly have a highly optimistic view of how informed and rational people's purchase decisions are. Heck, even lots of people on these forums make poorly informed purchase decisions (excluding those who come here after the fact to seek help, which is not an insignificant group). But most people don't frequent tech/PC forums. Trying to inform your way out of breaking compatibility is a fool's errand, will inevitably mostly reach the people who already understand the issue (as those are far more likely to seek out these channels of information anyhow), and ignores entirely the game of telephone that is public discourse on any topic. Things get lost or transformed in transmission, and there's no amount of marketing or clear communication that can realistically overcome this. It can make a positive impact vs. doing nothing at all, but the problem will by no means go away.


The red spirit said:


> That's because it's a pressure design, give that extra thickness to airflow design and it may do wonders.


That doesn't really make sense. The main benefit of a thicker fan is allowing for more pressure, as the thickness minimizes the effects of back-pressure resisting flow or flowing back between the blades. Also, if you look at the specs, it isn't really a pressure design - the 2200rpm 25mm Vardar is rated for 3.16mmH2O, while the 1800rpm 38mm Meltemi is rated for 2.75mmH2O. At speeds this low with fans this large, there ultimately isn't much you can do without _drastically_ increasing thickness - in which case stacking two 25mm fans is cheaper, easier, and likely as good. The 3000rpm version of the Meltemi is far better at 7.13mmH2O, but ... yeah, I wouldn't want that in the same room as me. The Meltemi is designed for a specific use case: pull orientation on thick, restrictive radiators, where it supposedly outperforms thinner fans due to specifics of its flow pattern and geometries. But you can't read that kind of stuff off of a spec sheet.


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## AsRock (Jul 10, 2021)

80251 said:


> 10,000 RPM fans, yeah that's all Delta, SanAce and Nidec make. Maybe you should look at their product catalogs sometime and realize they manufacture all kinds of fans and blowers -- some of which don't even run at 12V.



Yeah i like Delta's, used to have a few how ever the blade of the 120mm x 38mm hit some thing and ripped right off ,  my other is a 92mm x 38 and still going strong 12+ years later.

Got a few few P12's static pressure on my v card and and do much better then a none static one.


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## Ominence (Jul 10, 2021)

AsRock said:


> my other is a 92mm x 38 and still going strong 12+ years later.


i still have a handful of nearly 2 decade old Sunon 5 blade and Panaflo 7 blade 120mm fans. ah sweet memories... they have noisy bearings regardless of rpms! the panaflos are 2 wire AMP versions, lol.


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## FireFox (Jul 10, 2021)

Valantar said:


> Likely not much. As @Ominence mentioned, fans are typically rated at +/- 10% rotational speed, so if rated at 1500rpm it might top out at anywhere from 1350 to 1650rpm. Of course if it tops out at 1500rpm actual rotation speed at the rated voltage and 100% PWM and you have to overvolt them to run them faster, that might cause the motor to wear out faster. Likely not much from such a small change though. A fan rated at 12V operation can often handle much higher (15-16V at least) for short periods, so a low overvoltage over time is likely entirely within its tolerances.


So that means that if they are rated 1500rpm and can do 1650rpm because the extra 10% i can run it at that speed for 5 hours without any consequences?


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## Ominence (Jul 10, 2021)

FireFox said:


> i can run it at that speed for 5 hours without any consequences?


even at their stock 12v current draw (meaning 100% duty cycle) , they should last the MTBF of your fan. fans can be run 24/7 with the occasional (meaning many weeks in between) hub dust off to keep the bearings in a healthy condition. unless the fan is a noname bottom of the barrel variety, they are not as delicate as i think you might believe them to be.


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## FireFox (Jul 10, 2021)

Ominence said:


> even at their stock 12v current draw (meaning 100% duty cycle) , they should last the MTBF of your fan. fans can be run 24/7 with the occasional (meaning many weeks in between) hub dust off to keep the bearings in a healthy condition. unless the fan is a noname bottom of the barrel variety, they are not as delicate as i think you might believe them to be.


Thanks  for the info, appreciate it.
I just checked the operating Voltage of my fans which is 7V - 13.2V


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## Ominence (Jul 10, 2021)

FireFox said:


> 7V - 13.2V


no worries, in all likelihood your MB/PSU will not be suppling over 12.5v absolute max.


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## FireFox (Jul 10, 2021)

Ominence said:


> no worries, in all likelihood your MB/PSU will not be suppling over 12.5v absolute max.


Too many fans for the Motherboard


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## Valantar (Jul 10, 2021)

FireFox said:


> Thanks  for the info, appreciate it.
> I just checked the operating Voltage of my fans which is 7V - 13.2V


Remember that speed variance is static per fan though. I.e. if the spec says 1500rpm, any fan can top out at anywhere from 1350-1650 at its nominal voltage and 100% PWM and will go no lower/higher unless either of those values are changed. So it's essentially a lottery, mostly down to the specific physical properties of the fan motor and overall manufacturing variance. So if your fans _actually_ run at 1500rpm, that's where they top out, and they won't be rated to tolerate any higher. But they _are_ likely to be overbuilt for longevity, so chances of a slight overvolt to increase speeds actually doing any damage are slim. But the higher the voltage (above the rating), the faster the motor risks burning out.



FireFox said:


> Too many fans for the Motherboard


The 12V comes pretty much straight from your PSU though. So unless your PSU is _way_ out of ATX spec or you're using a boost converter, 12.something is what you're getting.


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## The red spirit (Jul 10, 2021)

claes said:


> And a little nudge again — try removing pci brackets to further reduce GPU noise. You may even be able to remove one set of fans after that mod


Not going to happen, I don't want it to look ghetto. I doubt that it will make any difference, Below graphics card, I have wifi card, so I probably only have one PCI cover left. It won't make any difference.



Andy Shiekh said:


> Not so sure, capacitors and fans seem to be the first thing to wear out for power supplies and one must catch a dry fan early for reoiling or the supply will overheat.
> 
> That said, I tend to recap what I have with top quality replacements and oil the fans with a lot more oil than they had originally; at that point I'd tend to agree with you.


I never seen a fan fail myself. I even have 14 year old case fan , it works. I have two cards with fans from 2004, they work. I have old AMD Athlon 64 cooler, fan still works. I only got defective fan from CM with water cooler, but after bypassing PWM pin it works fine. My dad had dead graphics cards fan on Sparkle FX 5200 twice, but it wasn't my computer and maybe it was dust build-up, which obviously he didn't clean. From my experience fans works a long time, very long time. Meanwhile the least reliable thing in computers is clearly motherboards. I have seen many failures and deaths of those things, they simply don't last. I don't know why exactly they die, but capacitors may be a suspect. But then, I haven't seen a failure of old PSU or graphics card, which also have tons of capacitors...



Andy Shiekh said:


> I believe the less blades on a propeller the more efficient.


I don't know about that, it doesn't seem correct. Right now, the best computer fans are Scythe Kaze Flex and they have 9 blades. I only seen 9800 rpm 3 blader, so maybe at those very high revs more blades is worse, but at lower revs there's no reason to think that.



FireFox said:


> Because we're talking about fans i have a question: if my fans are rated 1500rpm but i make them run at 1600rpm what could it happens to it?


Likely nothing, but if you raise their voltage too much, fans can burn.



Valantar said:


> Hm? I don't see how that's relevant. mITX is a standard. Heck, if anything, the SFF PC market is an excellent demonstration of how breaking standards leads to problems - try to google how many people have issues fitting the DTX Asus Crosshair 8 Impact into various SFF ITX cases, for example. SFF cases also tendt to be _very_ meticulous in documenting their clearances and limitations for non- or not-quite standardized things like radiator/fan fitment (not the size or mounting patterns, but if any can fit, how large, etc.), CPU cooler clearances, GPU size, etc. As for trying to make PCs smaller, the whole point is doing so _while maintaining compatibility_. Look at the Dan A4 for example - the entire purpose of that case is allowing you to build a powerful PC with all standard components - ITX motherboard, dual-slot full-size GPU, SFX PSU. All accepted standards. There are plenty of proprietary SFF solutions from the likes of Zotac, but you can't build those yourself. DIY requires adherence to standards to work.


Sure, I meant that mITX may be standard, but when it comes to cooling or graphics cards, it soon becomes wild west. That stuff causes tons of clearance issues and what? People still buy mITX boards and SFF cases. I don't see why thicker fans couldn't be sold.



Valantar said:


> But you're not accepting the inherent consequences of that, in (likely much) lower sales and limited compatibility. Of PC gamers (to pick a sizeable group with high performance PCs), only a small minority DIY build their PCs. Of those, only a small minority buy additional fans beyond those that come with their case. Of those, a large portion likely just buy whatever is cheapest as they discover free fan slots and are given advice online to just stuff it full of fans. So the people doing targeted purchases of brand-name fans? That's already a very small group. Adding "use cases where a thicker fan will fit and provide tangible benefit" is likely to make the target market so small as to be near meaningless.


But somehow clearly luxury stuff like AIOs, RGB and other stuff sell. Even RTX 3090 and it doesn't make any logical sense either.



Valantar said:


> Meaning that with any significant R&D cost, these fans would become _ridiculously _expensive. High end 25mm fans like the NF-A12x25 are already ridiculously expensive.


That's only because Noctua overprices their ripped off Gentle Typhoons. Those fans are certainly not even worth 10 Euros. On fun note, in some tests Arctic P12 beat Noctuas in noise and performance and they sell their fans for about 5 Euros. Do you honestly think that Noctua isn't ripping off?

And BTW what RnD? Is just stretching already existing designs so expensive?



Valantar said:


> Starting from scratch with literally every single part of the fan for a >35mm fan? I wouldn't be surprised if that doubled the costs from there.


You keep talking like thicker fans don't exist. Servers, cars, fridges and other things already have thicker fans. It's certainly not a Herculean task to make 40mm fans. And I said that someone has already done that. 




Valantar said:


> You clearly have a highly optimistic view of how informed and rational people's purchase decisions are. Heck, even lots of people on these forums make poorly informed purchase decisions (excluding those who come here after the fact to seek help, which is not an insignificant group). But most people don't frequent tech/PC forums. Trying to inform your way out of breaking compatibility is a fool's errand, will inevitably mostly reach the people who already understand the issue (as those are far more likely to seek out these channels of information anyhow), and ignores entirely the game of telephone that is public discourse on any topic. Things get lost or transformed in transmission, and there's no amount of marketing or clear communication that can realistically overcome this. It can make a positive impact vs. doing nothing at all, but the problem will by no means go away.


With such thinking, you won't achieve anything. That's all I can say here. You know, there wouldn't be PCs if someone hadn't broken standard.




Valantar said:


> That doesn't really make sense. The main benefit of a thicker fan is allowing for more pressure, as the thickness minimizes the effects of back-pressure resisting flow or flowing back between the blades. Also, if you look at the specs, it isn't really a pressure design - the 2200rpm 25mm Vardar is rated for 3.16mmH2O, while the 1800rpm 38mm Meltemi is rated for 2.75mmH2O.


Well I look at blade shape and they clearly look like Silencio FP's, which is pressure oriented design. BTW you said that pressure is measured while fans are completely blocked, Meltemis may not lose as much pressure as generic 7 blader at higher speed, which is what you want in radiator.


----------



## 80-watt Hamster (Jul 10, 2021)

The red spirit said:


> I never seen a fan fail myself. I even have 14 year old case fan , it works. I have two cards with fans from 2004, they work. I have old AMD Athlon 64 cooler, fan still works. I only got defective fan from CM with water cooler, but after bypassing PWM pin it works fine. My dad had dead graphics cards fan on Sparkle FX 5200 twice, but it wasn't my computer and maybe it was dust build-up, which obviously he didn't clean. From my experience fans works a long time, very long time. Meanwhile the least reliable thing in computers is clearly motherboards. I have seen many failures and deaths of those things, they simply don't last. I don't know why exactly they die, but capacitors may be a suspect. But then, I haven't seen a failure of old PSU or graphics card, which also have tons of capacitors...



Consider yourself fortunate.  Very few fans have 100% failed on me, but a significant proportion started making unpleasant noises a few years (or sometimes a few months or even weeks!) into their life.  CM, Cougar, Sunon, Yate Loon, Arctic, Enermax, Delta, it can happen to any of them.  My dataset isn't large enough to propose any trends, though.


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## The red spirit (Jul 10, 2021)

80-watt Hamster said:


> Consider yourself fortunate.  Very few fans have 100% failed on me, but a significant proportion started making unpleasant noises a few years (or sometimes a few months or even weeks!) into their life.  CM, Cougar, Sunon, Yate Loon, Arctic, Enermax, Delta, it can happen to any of them.  My dataset isn't large enough to propose any trends, though.


I probably don't even notice any new noise and I wouldn't consider that a complete failure either. Meh. The only noisier fan that I have is ATi X800 Pro, which made awful grinding noise, when I got it from eBay. Once I cleaned it up and reoiled, it works a lot better.

I'm probably no-lifing again, but I decided to watch some fan comparisons and see what they found out:









































I honestly give up. This is bullshit. I don't get it, how couldn't they all find one definitive winner. This doesn't make any sense. Most fans no matter how different their blade shape is, perform very similarly anyway. I hope that I'm missing something and somebody will correct me, but currently I'm just confused.


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## Shrek (Jul 10, 2021)

If there is more than one criterion there may not be a definitive winner; makes sense to me.

One may get better air flow at the expense of noise; perhaps one needs the flow and are not worried about the noise, or it could be the other way around.


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## The red spirit (Jul 10, 2021)

Andy Shiekh said:


> If there is more than one criterion there may not be a definitive winner; makes sense to me.


They don't even agree on quietest, radiator, air cooler and case fans. Other than Corsair ML and BQ Shadowings are poor.


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## Shrek (Jul 10, 2021)

Quietest is also relative; one trick is to spread the noise across the spectrum and it is then perceived as quieter by the ear.

This can be done with asymmetric fan blades.
Patent filings detail Retina MacBook Pro's quiet asymmetric fans | AppleInsider


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## The red spirit (Jul 10, 2021)

@Valantar I managed to find those very thick fans. Turns out they were Feser Triebwerk TK-121.

You can read about them here:








						What's the best 120mm case fan? | bit-tech.net
					

We've collected 22 120mm fans and put them through rigorous noise and airflow tests to see which is the best. Read on to see how to keep your hardware cool while keeping the noise your PC makes to a minimum.




					www.bit-tech.net
				




Turns out that Feser and NoiseBLocker have teamed up with goal to create radiator fan. It seems that nothing good came out out of that. They just made very thick fan and it doesn't particularly perform well. Oh well, perhaps only diameter matters for computer fans.



Andy Shiekh said:


> Quietest is also relative; one trick is to spread the noise across the spectrum and it is then perceived as quieter by the ear.
> 
> This can be done with asymmetric fan blades.


Did you really watch those reviews?


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## Shrek (Jul 10, 2021)

I don't have an hour to spare; sorry.


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## The red spirit (Jul 10, 2021)

Andy Shiekh said:


> I don't have an hour to spare; sorry.


Sorry mate, but until you have an hour to spare, there's no such thing as best fan.


----------



## looniam (Jul 10, 2021)

Ominence said:


> twin blade prop vs jet turbine for efficiency....any fluid dynamicists here?? i do realise that jets do not directly create airflow over the wings.
> 
> 
> probably should be fuel per thrust unit, of the blade and drive unit, or something similar.


propellers much like jets, are there for propulsion to fight drag, the lift is provided as the (whole!) wing goes through the air. NASA has a lot of good stuff if you have the time to get lost over there:


			Index of Aerodynamics Slides
		


(Eoops this is more direct https://www.grc.nasa.gov/www/k-12/airplane/lift1.html
cheers


----------



## mtcn77 (Jul 10, 2021)

The red spirit said:


> I probably don't even notice any new noise and I wouldn't consider that a complete failure either. Meh. The only noisier fan that I have is ATi X800 Pro, which made awful grinding noise, when I got it from eBay. Once I cleaned it up and reoiled, it works a lot better.
> 
> I'm probably no-lifing again, but I decided to watch some fan comparisons and see what they found out:
> 
> ...


If you would look at Arctic P12's air flow to pressure graph in their website, it has a specific impedance spot where air flow decreases and pressure increases. It looks unnoticable to the eye, but if you read up on it, to keep the motor silent and not overload, you have to keep at a specific side of the curve, so the fan works louder unequivocally due to turbulence when impedance contrarily decreases.
That puts the practical limit to silent operation, not some other dynamic variable - impedance is what costs most fans a top spot. You cannot increase fan speed because impedance increases, or some form of it. Don't just listen to streaming reviews, you'll find more substance in written media.
PS: 


> Above the optimum range of operation, the flow across the upper and lower sides of the impeller blades becomes turbulent and the impeller starts to go into an aerodynamic stall.
> 
> 
> 
> ...


----------



## Shrek (Jul 10, 2021)

The red spirit said:


> As far as I understand this is the formula of fan airflow:
> air moved = rpms*volume of air that fan blades catch per revolution*static pressure of fan


Where did you get this from? I am not even sure it is dimensionally correct.


----------



## mtcn77 (Jul 10, 2021)

You should try to keep impedance low. Fixed that mistake in my previous post. Not all fans are good pressure fans because of it. If you see a good "kink" in the pressure curve, it is going to be a loud "stalling" fan.


----------



## The red spirit (Jul 10, 2021)

mtcn77 said:


> If you would look at Arctic P12's air flow to pressure graph in their website


What graph? There isn't one anywhere:








						P12 | Single fan | ACFAN00118A
					

Pressure-optimised 120 mm Fan




					www.arctic.de
				







mtcn77 said:


> Don't just listen to streaming reviews, you'll find more substance in written media.


Any example of that? It's actually difficult to find any written fan test.



mtcn77 said:


> You should try to keep impedance low.


Should I put my graphics card in trash bin? 



Andy Shiekh said:


> Where did you get this from? I am not even sure it is dimensionally correct.


I came up with this formula myself. It's probably not correct and I expect to be corrected here.


----------



## mtcn77 (Jul 10, 2021)

The red spirit said:


> What graph? There isn't one anywhere:
> 
> 
> 
> ...


It is there. Scroll to technical data. It comes in a pdf file.


----------



## Shrek (Jul 10, 2021)

The red spirit said:


> I came up with this formula myself.



If there was a formula we wouldn't need graphs.


----------



## The red spirit (Jul 10, 2021)

mtcn77 said:


> It is there. Scroll to technical data. It comes in a pdf file.


No, there isn't. Here's the pdf link:


			https://www.arctic.de/media/8a/c9/8a/1583844823/spec_sheet_P12_180917_r2_EN.pdf


----------



## mtcn77 (Jul 10, 2021)

The red spirit said:


> No, there isn't. Here's the pdf link:
> 
> 
> https://www.arctic.de/media/8a/c9/8a/1583844823/spec_sheet_P12_180917_r2_EN.pdf


Haha, wrong file. Told you.








						ARCTIC P12 - Documentation
					

Get detailed documentation for your ARCTIC P12. All available in downloadable format for your convenience.




					support.arctic.de


----------



## 80251 (Jul 10, 2021)

Andy Shiekh said:


> Quietest is also relative; one trick is to spread the noise across the spectrum and it is then perceived as quieter by the ear.
> 
> This can be done with asymmetric fan blades.
> Patent filings detail Retina MacBook Pro's quiet asymmetric fans | AppleInsider



But radiator fans don't spin all that fast and having asymmetric fans would cause balancing problems that would affect bearing life at higher RPM's.


----------



## The red spirit (Jul 10, 2021)

mtcn77 said:


> Haha, wrong file. Told you.
> 
> 
> 
> ...


Okay, but this graph shows mostly that when fan is nearly completely blocked, airflow curve is non linear. And maximum pressure is achieved at either very low rpms or when fan is 70% blocked.


----------



## Shrek (Jul 10, 2021)

80251 said:


> But radiator fans don't spin all that fast and having asymmetric fans would cause balancing problems that would affect bearing life at higher RPM's.


This one blade 'fan' is balanced


----------



## mtcn77 (Jul 10, 2021)

The red spirit said:


> Okay, but this graph shows mostly that when fan is nearly completely blocked, airflow curve is non linear. And maximum pressure is achieved at either very low rpms or when fan is 70% blocked.


Please, pay attention to what I said before the discussion convolutes further. You are pushing up a case where I demonstrated the opposite. It will stall and not operate quietly. And it will also increase the load and burn the motor. You are free to try at your own behest. Just don't take it further.


----------



## 80251 (Jul 11, 2021)

Andy Shiekh said:


> This one blade 'fan' is balanced


I'd like to see that thing fly -- from a safe distance.

You'll notice that by the end of the war all the high-performance, allied, single, piston-engined fighter aircraft were using gigantic, paddle-bladed, 4-prop, steel propellers.

Aren't those heavy, asymmetric, direct driven, metal radiator fans a thing of the past? It seems like most automotive radiators now use lightweight electric fans.


----------



## agent_x007 (Jul 11, 2021)

The red spirit said:


> Because those high CFM fans spin at crazy rpms and are loud, if not outright burning every motherboards' fan connectors. You know, they have maximum power ratings too and they surely aren't made to handle 20+ watt fans.


Sorry for quality, it's video from 6 years ago (fans stil work no problem in this configuration) :








Short version :
Get a PWM high speed fan, pull 12V and GND from it's connector and stick it into Molex 12V and one of it's GND (leaving PWM and FanTach to MB).
Profit 
PS. I exchanged push fan for TFC1212DE in 2017. In 2015 (on this video), it was still FFC1212DE.


----------



## The red spirit (Jul 11, 2021)

agent_x007 said:


> Short version :
> Get a PWM high speed fan, pull 12V and GND from it's connector and stick it into Molex 12V and one of it's GND (leaving PWM and FanTach to MB).
> Profit
> PS. I exchanged push fan for TFC1212DE in 2017. In 2015 (on this video), it was still FFC1212DE.


I don't want that. Why would I ever want such a noisy PC? My CPU fan works within this rpm range 300-1200. Pretty much never it reaches maximum RPMs. A bit different subject is RX 580, because I can't change its cooling and PWM logic, but I can adjust power limit (and some other things) in vBIOS. Anyway, that's off-topic, all I want to know here is why fans perform the way they do.


----------



## mtcn77 (Jul 11, 2021)

I'm sure the issue why some fans can't push the radiator air is settled. It is okay to have preferences, but those preferences doesn't always reflect their sound profile consequences. Otherwise, we would see Noiseblocker eLoops dethroned by other fans - some with stator rings more centrally placed in the rotor frame, or some even without it. Not going to happen in truth. Sound vs. pressure balance takes no compromise.


----------



## freeagent (Jul 11, 2021)

The red spirit said:


> Why would I ever want such a noisy PC?


Because high performance and silence don't go hand in hand.


----------



## The red spirit (Jul 11, 2021)

freeagent said:


> Because high performance and silence don't go hand in hand.


Do you honestly think that someone like me, who own i5 10400F and detuned RX 580 really cares about performance much? Anyway, can this shit end? This is off-topic and if you wanna say something, then say something about fan airflow or pressure and why fans perform the way they do. This is interesting, not some server equipment.



mtcn77 said:


> I'm sure the issue why some fans can't push the radiator air is settled.


Sort of. It still bothers me that the only "push through radiator" metric we have is static pressure. Fan spins, it's not static and radiator isn't completely blocking airflow. It still doesn't make sense to me to use static pressure, instead of pressure at different rpms, as well as airflow at different rpms.



mtcn77 said:


> It is okay to have preferences, but those preferences doesn't always reflect their sound profile consequences. Otherwise, we would see Noiseblocker eLoops dethroned by other fans - some with stator rings more centrally placed in the rotor frame, or some even without it. Not going to happen in truth. Sound vs. pressure balance takes no compromise.


I actually wonder how would eLoops perform at 3000 rpm, just for data.


----------



## mtcn77 (Jul 11, 2021)

The red spirit said:


> Fan spins, it's not static and radiator isn't completely blocking airflow. It still doesn't make sense to me to use static pressure, instead of pressure at different rpms.


When you look at a p/q curve, it is actually an impedance/q curve. You cannot set the radiator fin gap by alternating the fan rpm. You have grown accustomed to thinking you can fix it. It is particular to the fan characteristic.



The red spirit said:


> I actually wonder how would eLoops perform at 3000 rpm, just for data.


Not that well. They can enter the charts at ~1500rpm, they aren't particularly good when noise is present, stator rings have their own frontal section which block free flow of air at high velocity. They just meet turbulent area with efficient operation area better. They aren't case fans per se.


----------



## The red spirit (Jul 11, 2021)

mtcn77 said:


> When you look at a p/q curve, it is actually an impedance/q curve. You cannot set the radiator fin gap by alternating the fan rpm. You have grown accustomed to thinking you can fix it. It is particular to the fan characteristic.


Still, so many sources call that static pressure. And those charts are made at fixed rpms. 



mtcn77 said:


> Not that well. They can enter the charts at ~1500rpm, they aren't particularly good when noise is present, stator rings have their own frontal section which block free flow of air at high velocity. They just meet turbulent area with efficient operation area better. They aren't case fans per se.


But at low rpms, they are kinda good. Say what you want, but they look really cool.


----------



## mtcn77 (Jul 11, 2021)

The red spirit said:


> But at low rpms, they are kinda good. Say what you want, but they look really cool.


That is the point. Every fan until its impeller's stall speed is good. They also don't work that well in a pull configuration, that does not bring down their value one bit. It is just designed the way it is.


The red spirit said:


> Still, so many sources call that static pressure. And those charts are made at fixed rpms.


You should look inside the area of the curve. The rpm ranges make impedance variable efficiency peaks that form an incline inside the p/q curve. Rpm just changes the incline, the stall point to radiator restriction stays the same. Changing the rpm won't make it a pressure fan per se.


----------



## The red spirit (Jul 11, 2021)

mtcn77 said:


> That is the point. Every fan until its impeller's stall speed is good. They also don't work that well in a pull configuration, that does not bring down their value one bit. It is just designed the way it is.


That's because they are static pressure fans. As I understand good static pressure fans are always good for pushing air through stuff, but may not be so great at pulling.




mtcn77 said:


> You should look inside the area of the curve. The rpm ranges make impedance variable efficiency peaks that form an incline inside the p/q curve. Rpm just changes the incline, the stall point to radiator restriction stays the same. Changing the rpm won't make it a pressure fan per se.


Really?






It show that upping rpms, does indeed improve pressure and airflow. Stall point just shows that at certain impedance fan will be working sub-optimally, meaning that it will be in poorer pressure-airflow ratio at same rpm.


----------



## mtcn77 (Jul 11, 2021)

The red spirit said:


> Stall point just shows that at certain impedance


Yes, at certain restriction a.k.a front section "aerodynamic drag," the fan will start to stall the same as it does in a pull configuration.

These fans cannot break aerodynamics. If they accelerate air more than a certain limit, turbulence begins and voids happen in the impeller tail and front flow. If there weren't any pressure change, there wouldn't be any sound. All development is to fall within these limits, not break them.
PS: the fan you demonstrate is pretty good by the way. It is self-correcting which makes me guess it is backward curved.


----------



## The red spirit (Jul 11, 2021)

mtcn77 said:


> Yes, at certain restriction a.k.a front section "aerodynamic drag," the fan will start to stall the same as it does in a pull configuration.


I meant it more alongside of air filter in front of it, closed doors or it blowing on radiator or cooler. I didn't mean frontal area. Frontal are mostly doesn't mater for consumers fans for simple reason, because it becomes a restriction at higher airflow situations. Most consumer fans don't spin that fast for frontal area to matter, however, I referenced 9800 rpm server fan and it had only three blades and certainly didn't have spinning disc around it like eLoops.

When I was reading about other fans today, I found out that other fans and fan alike things (like planes) have less blades, when they are engineered to spin very fast and move a much air, when there's no obstruction. Imagine something like aircraft 3 blade propeller or ceiling fan. More blades are added, when fan is designed to have more pressure. More blades is more pressure, but less maximum airflow. You can also make flat blades and turns out that they are better at moving more air, but at cost of noise. So what I found out, is that computer fans are mostly very similar to each other, is due to specific requirements for it. Generic 7 blader is the way it is is to provide a adequate amount of pressure and provide decent air flow at, relatively to other things, low revs and low noise level. 7 blades gives it pressure, non flat blades reduce noise, and while frontal are of it isn't small, it still provides okay air flow. It's very hard to actually increase airflow of fan due to noise restrictions of computer users. There's not much of what you can do. You can make fan spin faster or grow in diameter. Most fancy fan designs add more blades, make blade shape different and that's due to them trying to figure out how to reduce noise or to increase pressure. There clearly aren't many pure airflow oriented designs and for good reason, because computer is restrictive and airflow oriented designs just wouldn't work, due to their lack of static pressure or due to their higher noise. All things considered, eLoops in theory should be great, if you want quiet and pressure oriented fans. Meanwhile something like Noctua S12 series should be good as high airflow fans, maybe at slightly lower noise levels, but only if they are used with minimal restrictions otherwise it will perform worse than even the generic 7 blader.



mtcn77 said:


> PS: the fan you demonstrate is pretty good by the way. It is self-correcting which makes me guess it is backward curved.


Sorry, I have no idea what fan is referenced in this illustration. I found it on rage3D forum, when some user commented that computer fan manufacturers don't provide enough data. That makes me think, that it may not even be a computer fan or it is some industrial fan. Considering that it tops out at 2100 rpm, it may be some low end server fan and it's most likely generic 7 blader, because most server fans are generic 7 bladers. Only small fans or super fast fans aren't 7 bladers.


----------



## mtcn77 (Jul 11, 2021)

The red spirit said:


> I meant it more alongside of air filter in front of it, closed doors or it blowing on radiator or cooler. I didn't mean frontal area. Frontal are mostly doesn't mater for consumers fans for simple reason, because it becomes a restriction at higher airflow situations. Most consumer fans don't spin that fast for frontal area to matter, however, I referenced 9800 rpm server fan and it had only three blades and certainly didn't have spinning disc around it like eLoops.
> 
> When I was reading about other fans today, I found out that other fans and fan alike things (like planes) have less blades, when they are engineered to spin very fast and move a much air, when there's no obstruction. Imagine something like aircraft 3 blade propeller or ceiling fan. More blades are added, when fan is designed to have more pressure. More blades is more pressure, but less maximum airflow. You can also make flat blades and turns out that they are better at moving more air, but at cost of noise. So what I found out, is that computer fans are mostly very similar to each other, is due to specific requirements for it. Generic 7 blader is the way it is is to provide a adequate amount of pressure and provide decent air flow at, relatively to other things, low revs and low noise level. 7 blades gives it pressure, non flat blades reduce noise, and while frontal are of it isn't small, it still provides okay air flow. It's very hard to actually increase airflow of fan due to noise restrictions of computer users. There's not much of what you can do. You can make fan spin faster or grow in diameter. Most fancy fan designs add more blades, make blade shape different and that's due to them trying to figure out how to reduce noise or to increase pressure. There clearly aren't many pure airflow oriented designs and for good reason, because computer is restrictive and airflow oriented designs just wouldn't work, due to their lack of static pressure or due to their higher noise. All things considered, eLoops in theory should be great, if you want quiet and pressure oriented fans. Meanwhile something like Noctua S12 series should be good as high airflow fans, maybe at slightly lower noise levels, but only if they are used with minimal restrictions otherwise it will perform worse than even the generic 7 blader.
> 
> ...


Frontal area "drag coefficient" means all that restriction in front of the fan - filters, grills - and rear area drag means general air impedance - shrouds, radiators - stalling the fan, so eLoops don't work in pull configuration for the same reason any other fan doesn't. It is just air impedance costing you noise.

You can make the same fpm from a fewer blade count, but the trail velocity would have to compensate which would incur more turbulence at the trail edge.

I forgot that fans operate very linearly when in turbulent flow, so noise and performance, such as your example fan, don't mix all that well which brings us to the same conclusion about consumer fans being temperamental about drag coefficient.


----------



## Shrek (Jul 11, 2021)

80251 said:


> I'd like to see that thing fly -- from a safe distance.
> 
> Aren't those heavy, asymmetric, direct driven, metal radiator fans a thing of the past? It seems like most automotive radiators now use lightweight electric fans.


I just found it amazing that people took it to such an extreme; but asymmetric computer fans are very much things of the present.

I think the Russian's use counter rotating propellers, trading complexity for efficiency.

Howard Hughes crashed in an XF 11 with counter rotating props; I think a pitch control failure caused the props to be blowing in opposite directions.


----------



## mtcn77 (Jul 11, 2021)

Andy Shiekh said:


> I think the Russian's use *counter* rotating propellers, trading complexity for efficiency.


Not a good example. Like vane axials, they cannot compound each other when turning in the same direction, especially for pressure building.


----------



## The red spirit (Jul 11, 2021)

Andy Shiekh said:


> I think the Russian's use counter rotating propellers, trading complexity for efficiency.


That's what Scythe Fuma 2 does too.


----------



## Shrek (Jul 11, 2021)

Fascinating, but I suspect the price of counter-rotating fans is extra noise; but I could well be wrong.


----------



## Ominence (Jul 11, 2021)

The red spirit said:


> I use two Silencio FP fans at 1080 rpms


your Silencios seem a good pressure optimsed fit for your sensory deprivation cube experience. i found this link kinda interesting.

Table chart sound pressure levels SPL level test normal voice sound levels pressure sound intensity ratio decibel comparison chart conversion of sound pressure to sound intensity noise sound units decibel level comparison of common sounds calculation compression rarefaction loudness decibel dB scale ratio factor unit examples - sengpielaudio Sengpiel Berlin

i have old noiseblockers as well so the eloops discussion is also somewhat interesting. i tried an interesting experiment some 4 years ago- Noiseblocker black silent pro 140mm 1700rpm. But my 18 fans sound like this on idle, 7v i think, 1 inch distance. this is a push pull arrangement sandwiching a watercool 420 pro stainless rad.


----------



## freeagent (Jul 11, 2021)

The red spirit said:


> Do you honestly think that someone like me, who own i5 10400F and detuned RX 580 really cares about performance much? Anyway, can this shit end


I don’t know what equipment you have. I did see those sweet Delta’s though. Enjoy your adventure


----------



## 80251 (Jul 11, 2021)

The red spirit said:


> I don't want that. Why would I ever want such a noisy PC? My CPU fan works within this rpm range 300-1200. Pretty much never it reaches maximum RPMs. A bit different subject is RX 580, because I can't change its cooling and PWM logic, but I can adjust power limit (and some other things) in vBIOS. Anyway, that's off-topic, all I want to know here is why fans perform the way they do.


Thicker fans can spin slower and still produce more CFM and static pressure than a thin fan -- at the same RPM. Whether or not it would also produce less noise is anyone's guess.


----------



## Shrek (Jul 11, 2021)

I think it is fair to say that slower is quieter, although shape plays a role.


----------



## Ominence (Jul 11, 2021)

hopefully we are all talking terminologies more correctly than the other way round.
fan diameter and fan thickness should not be confused.
in a fan advertised as being 120x120x25 in the specs, the fan dia is 120mm (the swept area) and fan thickness is 25mm which then leads to the swept volume calculation of the fan.


----------



## mtcn77 (Jul 11, 2021)

Ominence said:


> hopefully we are all talking terminologies more correctly than the other way round.
> fan diameter and fan thickness should not be confused.
> in a fan advertised as being 120x120x25 in the specs, the fan dia is 120mm (the swept area) and fan thickness is 25mm which then leads to the swept volume calculation of the fan.


Obviously, the more blade area there is, the more spherical the blades are in shape. Other than that, shaping them in constant overlying flow acceleration is the practical limit, imo. I think altitude matters for this scenario, but cannot tell in which direction. We would have split blades if it came to that.


----------



## The red spirit (Jul 11, 2021)

Andy Shiekh said:


> Fascinating, but I suspect the price of counter-rotating fans is extra noise; but I could well be wrong.


They aren't any more noisier than any other fans. Come on, it's Scythe. They are specializing in quiet and powerful cooling solutions far more than other brands. Anyway, if yo uare interested in Fuma 2, you have to watch these two videos, they explain everything:

















TL;DR is that it performs great and is very quiet, it's also great value for money. It performs like highest end dual tower coolers (minus 140mm models) and is at top or near top of quietness charts. Mostly due to the fact that Scythe just puts rather slow fans on it.


----------



## Shrek (Jul 11, 2021)

Well, I don't quite consider this straight counter rotating as the air is straightened out in-between by fins.


----------



## Ominence (Jul 11, 2021)

smaller dia fans are generally poor performing due to them having a bigger ratio of the hub sacrificing wind swept volume.


mtcn77 said:


> Obviously, the more blade area there is, the more spherical the blades are in shape. Other than that, shaping them in constant overlying flow acceleration is the practical limit, imo. I think altitude matters for this scenario, but cannot tell in which direction.


it's interesting to see noctua have 2 very different fans with one optimised for airflow and the other for static pressure at the same rpm but not the same noise profile? seems to me that AF is noiser than SP??














the SB series is louder, less airflow and more pressure than the SA series, interesting!


----------



## mtcn77 (Jul 11, 2021)

Ominence said:


> the SB series is louder, less airflow and more pressure than the SA series, interesting!


Those charts aren't p/q curves. Loudness and pressure is against flow in that comparison. We are looking for the plateau.


----------



## Ominence (Jul 11, 2021)

mtcn77 said:


> Those charts aren't p/q curves. Loudness and pressure is against flow in that comparison.


yes, there is no curve there, they are absolute measurements with a few given constants in a lab environment.


----------



## eidairaman1 (Jul 11, 2021)

Higher Static pressure fans help push air through obstructions where as high cfm fan help flow air more quickly, so id say use high flows on less restrictive heatsinks and other areas.


----------



## Ominence (Jul 12, 2021)

i think the real trick here is that the more absolute airflow you actually have across your system, the louder and potentially cooler it will be (diminishing returns always apply, you will hit the ambient wall eventually). finding that perfect balance is the fine arts science we all have to work towards- balancing noise and temps (and from there, system longevity and performance).


----------



## Shrek (Jul 12, 2021)

I would like to know if turbulence helps with heat pick-up


----------



## Ominence (Jul 12, 2021)

mtcn77 said:


> I think altitude matters for this scenario


jets, more blades, more thrust- better than props for high altitude performance. haven't seen a high service ceiling propcraft anytime recently.



Andy Shiekh said:


> turbulence helps with heat pick-up


i don't quite catch your query but the more turbulence there is, the more variable restriction would apply to the fan motor torque which could lead to very slow heat buildup. any inconsistencies in the fan speed due to external factors will lead to friction forces/resistance and therefore heat to potentially generate above nominal. however, the design of the motor should take into account such factors and be within the operating range of its engineering spec.


----------



## Shrek (Jul 12, 2021)

I meant that if the fan output was turbulent, it would pick up heat more efficiently from a surface than if the impinging air was laminar, but I don't know if it would be a significant improvement.


----------



## mtcn77 (Jul 12, 2021)

Andy Shiekh said:


> I meant that if the fan output was turbulent, it would pick up heat more efficiently from a surface than if the impinging air was laminar, but I don't know if it would be significant.


That is at the fin interface.


----------



## Shrek (Jul 12, 2021)

Such a simple seeming device, the fan, but how complicated in reality.


----------



## mtcn77 (Jul 12, 2021)

Andy Shiekh said:


> Such a simple seeming device, the fan, but how complicated in reality.


Has to do with rotational versus forward velocity me thinks, just like helicopters.



Ominence said:


> jets, more blades, more thrust- better than props for high altitude performance. haven't seen a high service ceiling propcraft anytime recently.


Jets ignite fuel, cause a thrust. Propfans cannot make a pressure gradient from atmospheric thin air.


----------



## Ominence (Jul 12, 2021)

Andy Shiekh said:


> fan output was turbulent, it would pick up heat more efficiently from a heat sink than if the impinging air was laminar.


i think turbulence is not the key to better heat pickup. the magic scenario from a fluid dynamics perspective would be laminar flow right across and brushing the fins of the thermal exchange surface. this would ensure maximum constant density of airflow across the fin interface as @mtcn77 puts it and give the maximum effective thermal transference. this could be the reason why the new noctua fanless cooler has only 13fins to space the fins optimally from each other to allow effective convection to occur, whilst at the same time not allow the fins to feed heat off each other before being able to dissipate it to the air thru natural forces at play (potentially getting trapped in turbulence and slowing their escape speed leading to faster heat buildup and/or higher constant retained heat).



mtcn77 said:


> Jets ignite fuel, cause a thrust. Propfans cannot make a pressure gradient from atmospheric thin air.


well, they all seem to do something with the fuel so take your pick i guess.


----------



## mtcn77 (Jul 12, 2021)

Ominence said:


> i think turbulence is not the key to better heat pickup. the magic scenario from a fluid dynamics perspective would be laminar flow right across and brushing the fins of the thermal exchange surface. this would ensure maximum constant density of airflow across the fin interface as @mtcn77 puts it and give the maximum effective thermal transference. this could be the reason why the new noctua fanless cooler has only 13fins to space the fins optimally from each other to allow effective convection to occur, whilst at the same time not allow the fins to feed heat off each other before being able to dissipate it to the air thru natural forces at play (potentially getting trapped in turbulence and slowing their escape speed leading to faster heat buildup and/or higher constant retained heat).
> 
> 
> well, they all seem to do something with the fuel so take your pick i guess.
> ...


200iq stuff right there.

I recently watched a series why propfans are junk. Turns out they don't need Mercedes to produce their junk quality.


----------



## Ominence (Jul 12, 2021)

mtcn77 said:


> they don't need Mercedes


or BMW for that matter!


----------



## The red spirit (Jul 12, 2021)

Ominence said:


> i have old noiseblockers as well so the eloops discussion is also somewhat interesting. i tried an interesting experiment some 4 years ago- Noiseblocker black silent pro 140mm 1700rpm. But my 18 fans sound like this on idle, 7v i think, 1 inch distance. this is a push pull arrangement sandwiching a watercool 420 pro stainless rad.


Where do you even put so many fans? Is this an eATX case?



80251 said:


> Thicker fans can spin slower and still produce more CFM and static pressure than a thin fan -- at the same RPM. Whether or not it would also produce less noise is anyone's guess.


That's has been debunked. Thicker fans increase pressure, bigger diameter increases airflow. If you want to Google something, Google Feser Triebwerk fans, they were very thick (55mm) and they didn't really do anything special.



Andy Shiekh said:


> I would like to know if turbulence helps with heat pick-up


As far as I know, it seems that turbulence is bad, because turbulence is slower than laminar flow. If anything turbulence may trap heat.



Andy Shiekh said:


> Such a simple seeming device, the fan, but how complicated in reality.


I would like to say that, but nah it's really not. The main problem there is that it's very hard to find a correct and in depth information about such stuff. That and fan manufacturers trying to sell various fan designs as being better and often lying about that or at least not explaining in what specific situations it's the best design. But then again, I don't consider automotive aerodynamics difficult. To be honest, it's far easier to design a sleek car, rather than make 7 spinning blades into most efficient form.


----------



## Ominence (Jul 12, 2021)

The red spirit said:


> Where do you even put so many fans? Is this an eATX case?


external rad mate. fed into the case with tube grommets on the NZXT phantom OG.


----------



## freeagent (Jul 12, 2021)

Andy Shiekh said:


> I would like to know if turbulence helps with heat pick-up


I believe it does.. to a point. Lots of people value silence, I do to.. but when it’s time to work you have to make a little noise, or the silence will keep you in the slow lane. And that’s ok..


----------



## The red spirit (Jul 12, 2021)

freeagent said:


> I believe it does.. to a point. Lots of people value silence, I do to.. but when it’s time to work you have to make a little noise, or the silence will keep you in the slow lane. And that’s ok..


Or you just build completely passive system and have both performance and silence.



Ominence said:


> external rad mate. fed into the case with tube grommets on the NZXT phantom OG.
> 
> View attachment 207584


Is that car radiator?


----------



## Shrek (Jul 12, 2021)

freeagent said:


> I believe it does.. to a point. Lots of people value silence, I do to.. but when it’s time to work you have to make a little noise, or the silence will keep you in the slow lane. And that’s ok..


I'm with you on that; silence is a big deal.


----------



## freeagent (Jul 12, 2021)

The red spirit said:


> Or you just build completely passive system and have both performance and silence


Not the kind of performance I am used to.

Edit:

I do know a little about running semi passive. I was running my 3770K @ a solid 4500MHz on my Le Grand Macho RT with Linpack Xtreme and no CPU fan installed, case fans @ 5v  last winter.. I even tried my old 3600XT passively. It was ok @ 4400.


----------



## Ominence (Jul 12, 2021)

The red spirit said:


> Is that car radiator?


Watercool MO-RA3 420 Pro Stainless Steel, 269,95 €


----------



## formula383 (Jul 12, 2021)

"Airflow vs static pressure fans. Are they a scam?"​​No? How would they be a scam?​​Every fan has its use case and will fit into the market in some way. If you don't find a difference in fan design for your use then just get the fan you like the color of. But for others different types of fans can be of value.​​Things you need to keep in mind.​-   1    - We are limited by form factor.​-   2   - Noise is a large concern for PC fans.​-   3   - Moving air creates noise.​​There is only so much you can do in side of these restrictions.​​So i'm sure you are asking well WHERE would i use a SP fan. Thick, high FPI rads will do better with a SP style fan. If you use SP fans in a relatively open space they will have no positive effect. IE using a SP fan on a CPU cooler that was created for optimal air flow for low noise in a PC. Putting a SP fan on that cooler is going to show no benefit at all.

(edit: no idea why this post is all in bold its not marked as bold in the tools here..)​


----------



## The red spirit (Jul 12, 2021)

I have found some good stuff on Reddit about Airflow vs Static Pressure:

__
		https://www.reddit.com/r/buildapc/comments/6c3cla


----------



## doyll (Jul 12, 2021)

Air turbulence creates resistance to airflow, thus lowering airflow .. and mixing heated air with cooler air flowing through case .. thus increasing air temp .. thus this air can't absorb as much heat from components .. so components run hotter.   Every degree warmer airflow is through our cases means components will be same degrees hotter (at same load and fan speed / airflow).  
Air temp to component temp is an almost exactly 1:1 ratio (same load & same fan speed).

Higher pressure rated fans work will flow more air in our applications than higher airflow rated fans because higher pressure ratings mean more ability to overcome airflow resistance.  

To have "airflow" we have to have a pressure differential .. fans create higher pressure air on exhaust side .. this higher pressure air moves into lower pressure air creating airflow.  

If a fan made no pressure (0.0mm H2O) it would have no airflow.  The higher the pressure rating the more airflow fan will have in our cases because even a small round wire creates resistance.  

The lowest resistance grills are the wire ring kind, and even they restrict airflow of most fans by 25-35% .. and the lower the pressure rating a fan has the less air will flow through grill / case resistance.  

Keep in mind a fan rated 1.836mm H2O (only at full speed) has about the same pressure difference between intake side and exhaust side (at full speed) and there is between the pressure on your feet vs on your chest standing at sea level.  

Yeah, our fans create almost no pressure differential .. so have almost no ability to overcome resistance. 

Best way to understand how airflow works is to think  of air as being water .. the science of airflow is named "fluid dynamics" for a reason.  

Think of your case as a box under water with holes in  box as vents in a case .. propellers in some of the openings are fans in our cases.  For water to flow into box an equal amount of water has to flow out.  

We cannot move more air into our cases than we have coming out of our cases.  Simple physics.  

This does not mean we need both intake and exhaust fans .. because intake and exhaust fan in case are basically the same as push / pull fans on cooler or radiator.  Push / pull can improve overall airflow only because push / pull increase pressure rating, thus more ability to overcome resistance.


----------



## mtcn77 (Jul 12, 2021)

@The red spirit good stuff, but he took cfm at face value, not at optimal fan efficiency pq value.

Hi, @doyll!
A good fan has to have a good "jet", but not a lot of "wake" which causes turbulence. Wake is very detrimental to a good fan. Too much wake and a fan starts working in static pressure, making just noise and not a lot of air flow. We should look at its pq curve where it is just below its static pressure build up point.


----------



## doyll (Jul 12, 2021)

mtcn77 said:


> Hi, @doyll!
> A good fan has to have a good "jet", but not a lot of "wake" which causes turbulence. Wake is very detrimental to a good fan. Too much wake and a fan starts working in static pressure, making just noise and not a lot of air flow. We should look at its pq curve where it is just below its static pressure build up point.


I tried to simplify it as much as possible.  

Basically "airflow" is all about displacement ..  air moving from higher pressure are (at fan) to lower pressure area (farther away from fan. 
We can't move more air into our cases than is moving out of it.  

Our fans have such low static pressure ratings even at full speeds of 1300-1500rpm.  They make less static pressure / pressure differential than the difference in pressure on our chests vs on our feet standing at sea level) at full / maximum speed.   As most of us run our fans at 700-1000rpm (1/2-2/3rd of their full speed) lowers their pressure rating to about half of spec .. so about the smae as pressure on our butt vs on our feet.  That is extremely little ability to overcome any kind of resistance in our cases (grill, filter, cables, etc).

Therefore we need fans with as high a pressure rating as possible at the speed we will be running them.

Like I said, this is over-simplification.  While I understand your  "jet" and "wake" concept, they have little to no effect in our cases with HDD cage, GPU PCB and cooler, cables, RAM, etc. all disrupting  "Jet" & "wake" effects.  

I'm trying to get some equipment and samples together to compare how different impeller designs effect case airflow.  My guess is impellers like NF-A12x25 and TL-C14 (Thermalright) will give us better airflow through our cases than impellers like NF-A15 and TY-147.  Hopefully there will be enough difference it will show in test results.


----------



## mtcn77 (Jul 12, 2021)

doyll said:


> TY-147


Lol, Thermalright 147 can eat those 12cm fans for lunch. Take a look at "hardware.info".


doyll said:


> While I understand your "jet" and "wake" concept, they have little to no effect in our cases with HDD cage, GPU PCB and cooler, cables, RAM, etc. all disrupting "Jet" & "wake" effects.


How good of you to note, however jet and wake flows form the bulk of fan volute, so if it can't eject useful airflow, wake currents arise.

My personal take is that pressure optimised fans create a smaller volute, albeit a more resistant volute flow seperations due to wake formations.


----------



## The red spirit (Jul 12, 2021)

mtcn77 said:


> @The red spirit good stuff, but he took cfm at face value, not at optimal fan efficiency pq value.


I think that bigger downfall of that post is that fan spec data collection methods are undisclosed and they are likely aren't accurate. I dunno, I start to feel that generic 7 blader is one of the best fan shapes and everything else is trying to deviate from it for deviation's sake.



doyll said:


> I'm trying to get some equipment and samples together to compare how different impeller designs effect case airflow.  My guess is impellers like NF-A12x25 and TL-C14 (Thermalright) will give us better airflow through our cases than impellers like NF-A15 and TY-147.  Hopefully there will be enough difference it will show in test results.


If you decide to do any testing, please test generic 7 blade fan.


----------



## mtcn77 (Jul 12, 2021)

The red spirit said:


> I think that bigger downfall of that post is that fan spec data collection methods are undisclosed and they are likely aren't accurate. I dunno, I start to feel that generic 7 blader is one of the best fan shapes and everything else is trying to deviate from it for deviation's sake.


Total blade surface area can benefit from a lower blade count, considering fewer impeller blades have directly correlated less total trail circumference. The whole of the blade does not generate useful work. A bigger blade can increase the suction zone behind the leading edge, from what I gather air only moves to fill the atmospheric pressure behind the fan blade.

Just look at the plateau under the static pressure peak in pq curves. Its the most effective fan impedance curve point. It is both reliable and not very outlandish in cfm rating, basically ~%50.


----------



## cvaldes (Jul 12, 2021)

Ominence said:


> smaller dia fans are generally poor performing due to them having a bigger ratio of the hub sacrificing wind swept volume.
> 
> it's interesting to see noctua have 2 very different fans with one optimised for airflow and the other for static pressure at the same rpm but not the same noise profile? seems to me that AF is noiser than SP??
> 
> ...


Noctua has three primary fan designs not two.

NF-A__ - all-purpose, 9 blades
NF-F__ - static pressure optimized, 7 blades (these are the NF-P__ products in the redux line)
NF-S__ - airflow optimized, 7 blades

The S12A and S12B are have the same blade design however Noctua selected different parts (plastics, fan components) and subtracted a few details that makes the less-expensive redux-1200 product line slightly noisier. That's why they are so similar in performance.

Noctua themselves explain their fan differences in several articles:






						Which fan is right for me?
					

Designed in Austria, Noctua's premium cooling components are renowned for their superb quietness, exceptional performance and thoroughgoing quality.




					noctua.at
				









						NF-A12x25: performance comparison to NF-F12 and NF-S12A
					

Designed in Austria, Noctua's premium cooling components are renowned for their superb quietness, exceptional performance and thoroughgoing quality.




					noctua.at
				









						Noctua
					

In addition to our standard line-up of premium quality quiet cooling fans that feature all our latest technologies, come with a complete set of accessories and are easily recognisable by our signature brown colour scheme, we carry two extra product lines: redux & industrialPPC.




					noctua.at
				




Following Noctua's suggestions I use NF-F12 PWM fans on my radiators and NF-S12 PWM fans for chassis intake/exhaust in three PC cases. With my current fan curves, the fans all top out around 1000 rpm, well short of the maximum rotational speed (and thus noise). One build uses the grey NF-F12 fans on the radiators for aesthetic reasons. I don't actually own an NF-A12x25 all-purpose fans since I am using task-specific models.

In my NZXT H1 case I replaced the stock NZXT Aer 140mm fan with the NF-A14 industrialPPC-2000 PWM. Paired with a Low Noise Adapter cable and again with a fan curve that doesn't extend to the fan's maximum speed, this is considerably quieter than the stock fan.

In your table, you fail to recognize that the Low Speed variant of the NF-A12x25 provides barely half the airflow as the S12 models. So yes, the NF-A12x25 LS-PWM is quieter at full speed than the S12 it's moving considerably less air. A more realistic real world scenario would have the S12 fans running between 50-75% max speed which does knock down the noise substantially.


----------



## mtcn77 (Jul 12, 2021)

cvaldes said:


> Noctua has three primary fan designs not two.
> 
> NF-A__ - all-purpose, 9 blades
> NF-F__ - static pressure optimized, 7 blades (these are the NF-P__ products in the redux line)
> ...


Extreme fan designs do not pick up in consumer space for a reason. The demand is driven by all around laminar performance. It is hard to design a fan with no stall and as much performance as possible, yet the use case is very much limited to that.
We don't need too much "terminal" air velocity in order to avoid trail separation. What I have been thinking about is if Noctua launched these fans in opposite flow direction, so we could test out their different designs in series like vane axial fans working together, but different push-pull units.


----------



## cvaldes (Jul 12, 2021)

You can wish all you want but it is highly unlikely Noctua will be releasing opposite flow designs in the near future. The market for that item is exceptionally small; most PCs sold are pre-built. 

DIY builders are already a small subgroup of PC users and many are happy just buying the cheapest aRGB model. The performance focused enthusiasts are rare.


----------



## 80-watt Hamster (Jul 12, 2021)

cvaldes said:


> You can wish all you want but it is highly unlikely Noctua will be releasing opposite flow designs in the near future. The market for that item is exceptionally small; most PCs sold are pre-built.
> 
> DIY builders are already a small subgroup of PC users and many are happy just buying the cheapest aRGB model. The performance focused enthusiasts are rare.



Noctua may not, but Antec does.


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## mtcn77 (Jul 12, 2021)

80-watt Hamster said:


> Noctua may not, but Antec does.


The brands don't even need to be identically matched, it is just to match them in alternative push-pull setups to see which works.
PS: this could work. Antec, you, pc-friendly brand!


----------



## cvaldes (Jul 12, 2021)

Well then enjoy your Antec fan analysis. 

I was just addressing your comment about wishing that Noctua would ship this. They aren't. 

That said, I presume that Noctua has hundreds of prototypes of unreleased designs in their labs. Only a handful make it as shipping product. All of the good manufacturers do this: Apple, Samsung, HP, Lenovo, et al.

In fact, creating prototype opposite flow designs likely helps them design future versions of their products that ship today. Many of Noctua's current fans are iterations of older designs.


----------



## mtcn77 (Jul 12, 2021)

cvaldes said:


> DIY builders are already a small subgroup of PC users and many are happy just buying the cheapest aRGB model. The performance focused enthusiasts are rare.


You know, in my religious text, the literate are the few, yet the stronger of the bunch. Don't fret.


----------



## cvaldes (Jul 12, 2021)

Yes, DIY PC building is a religion.

That said, some are aggressive missionaries, others are Zen Buddhists.


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## mtcn77 (Jul 12, 2021)

cvaldes said:


> Yes, DIY PC building is a religion.


No, becoming a believer goes through being literate. Don't worry about which products "we" can make cool and trendy. Idiots follow wherever we go.


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## cvaldes (Jul 12, 2021)

No, for thousands of years believers of many religions all over the world were illiterate. In fact, it was helpful to keep your faithful largely ignorant. Thoughtful analysis and critical analysis of standing dogma results in disagreement.

But do enjoy those Antec fans.


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## mtcn77 (Jul 12, 2021)

cvaldes said:


> No, for thousands of years believers of many religions all over the world were illiterate. In fact, it was helpful to keep your faithful largely ignorant. Thoughtful analysis and critical analysis of standing dogma results in disagreement.
> 
> But do enjoy those Antec fans.


Not if you go look at what is written which isn't a matter of opinion. It is okay to hold the opinion that it is obfuscated by ambiguity, but it is very specific about the requirement of literacy and true belief being a virtue of that.
Like I said, until someone does it first, it cannot be trendy to do so, like believing it can be done.


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## cvaldes (Jul 12, 2021)

That's fine.

I just care that my builds are cool and quiet. I have accomplished this with my cooling implementation.

I can run a synthetic benchmark like Cinebench R23 or a real-world task like a Handbrake encode and my Ryzen 5900X remains cool and quiet. Same with my TUF Gaming GeForce 3080 under the Unigine Heaven benchmark or during actual game play.

This is a solved problem and didn't require rocket science.  I don't need a Ph.D. in aeronautical engineering or hydrodynamics. I do hope fan engineers have those degrees though.

If people want to make this more complicated than necessary, they are free to do so. I have better things to do with my time.


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## mtcn77 (Jul 12, 2021)

I just want to know rotor terminal velocity in correlation to axial velocity of air. Since air behaves with differences in velocities differently, 2 fans could accelerate it better than any one single design and not exceed the separation terminal velocity.

Okay, so... pumps are not any different than air cooling fans, what is next...


----------



## The red spirit (Jul 12, 2021)

cvaldes said:


> If people want to make this more complicated than necessary, they are free to do so. I have better things to do with my time.


Sorry mate, but in this thread there's a desire to find out why fans are the way they are and why that matters (or doesn't).


----------



## Shrek (Jul 12, 2021)

Laptops use centrifugal fans, but are there any such fans for desktop use?


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## The red spirit (Jul 12, 2021)

Andy Shiekh said:


> Laptops use centrifugal fans, but are there any such fans for desktop use?


Blower GPUs? This thing:





This Dell:




Cooler Master Jet:


----------



## cvaldes (Jul 12, 2021)

The centrifugal fan design is inferior in airflow which is why it's primarily used where space is at a premium. If I recall correctly, this style of fan is also noisier.

Some GPUs have blower-style fans because it is expected that the card will be deployed in a system that lives in a climate controlled server room where noise isn't an issue. Usually those are cards that are designed to be installed in 2 PCIe slots so having a louder cooling solution is preferable to eating up more real estate.


----------



## freeagent (Jul 12, 2021)

I had that Jet 7+ on my old axp-m 2500. It made a whistle sound just off idle so about 17-1800rpm. It was pretty decent. Lots of copper on a bare die was helpful with that insane clamping force lol.. The advantage was supposed to be no dead spot.


----------



## mtcn77 (Jul 12, 2021)

cvaldes said:


> Some GPUs have blower-style fans because it is expected that the card will be deployed in a system that lives in a climate controlled server room where noise isn't an issue.


Actually, this type of forward inclined radial fans are self cleaning compared to backward inclined fans which surprisingly have a higher efficiency, if I recall correct. Also, they are quiet compared to forward inclined radials. Their only handicap is they are sensitive to dust wearing their impeller.
PS: this thread could not have taken off as the only nut job being myself. As shown here, there are other people with fan daydreams.


----------



## The red spirit (Jul 12, 2021)

freeagent said:


> I had that Jet 7+ on my old axp-m 2500. It made a whistle sound just off idle so about 17-1800rpm. It was pretty decent. Lots of copper on a bare die was helpful with that insane clamping force lol.. The advantage was supposed to be no dead spot.


But the main question is, did it sound like jet?


----------



## freeagent (Jul 12, 2021)

The red spirit said:


> But the main question is, did it sound like jet?


It did kind of lol! That whistle was annoying AF. I still have it in a box somewhere lol..


----------



## formula383 (Jul 12, 2021)

The squirrel cage fans are actually really quiet for the work they do(some are just very poorly designed), the reason everyone hates them in pc's is because they are using far to small of a fin stack to cool the amount of heat being produced by the gpu. Well that and previously they had very bad design compared to the newer blower cool style gpu's. Of course the cage style fans are best under higher pressure applications.


----------



## Ominence (Jul 12, 2021)

cvaldes said:


> Noctua has three primary fan designs not two.
> 
> NF-A__ - all-purpose, 9 blades
> NF-F__ - static pressure optimized, 7 blades (these are the NF-P__ products in the redux line)
> NF-S__ - airflow optimized, 7 blades


i did not say whether they did or not. to clarify, i was comparing these particular size and speed aspect constants of those specific fans. i would have included Fs if they had matching specs. i think people know that noctua do not have just 3 fan SKUs on offer.
120x120x25mm
1200rpm


cvaldes said:


> In your table, you fail to recognize that the Low Speed variant of the NF-A12x25 provides barely half the airflow as the S12 models. So yes, the NF-A12x25 LS-PWM is quieter at full speed than the S12 it's moving considerably less air.


that is where the difference between an AF and SP optimised fan at the same rotational speed and size is highlighted. the NFA being balanced (therefore more P and less A than the NFS and since the absolute volume of air the NFA moves is less than the NFS- the NFA is quieter too).


cvaldes said:


> A more realistic real world scenario would have the S12 fans running between 50-75% max speed which does knock down the noise substantially.


i'm talking about advertised performance with a few given constants to check against a few advertised variables in a lab test environment. changing fan speed would be a critical error in making that comparison.

i have their highest absolute flowing and pressure NFA14 3k fans that can run down to about 800rpm so completely happy with my setup flexibility. i prefer the ability to brute force with a bit of tact as well. as a bonus they are black so go well with the case aesthetics.


----------



## 80251 (Jul 13, 2021)

The red spirit said:


> That's has been debunked. Thicker fans increase pressure, bigger diameter increases airflow. If you want to Google something, Google Feser Triebwerk fans, they were very thick (55mm) and they didn't really do anything special.


I hate to disagree but the Delta FFB1424HHG 140x50mm vaneaxial fan at 2800 RPM produces more static pressure and CFM than the Noctua NF-A14 at 3000 RPM.  219.73 CFM vs. 159 CFM and 12.84mm-H2O vs. 10.52mm-H2O.


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## cvaldes (Jul 13, 2021)

Again, who (DIY PC builders) runs their fans at full RPMs?

And even if you are getting more CFMs or mm-H2O static pressure, in most typical PC builds, the benefit from the custom loop ends far before one reaches the components' maximum settings.

I realize that the Internet is full of geeks who like to nerd out on a bunch of numbers than follow real world usage.

I posted actual numbers from several of my builds and I am satisfied with what I have achieved. I know some of my builds aren't particularly cost effective but I'm okay with spending a few dollars in the interest of education/experience.

I'm not trying to send a rocket to Mars. I'm just trying to quietly cool my gaming PC. I did that. Problem solved (in my case) with a budget and time/effort metric that is still acceptable. It's not like I'm going to spend two months trying to shave 1 degree Celsius off.

That would be stupid. I'm not a competitive overclocker. And those who are wouldn't participate in garbage discussions like this.


----------



## freeagent (Jul 13, 2021)

cvaldes said:


> Again, who (DIY PC builders) runs their fans at full RPMs?


If you overclocked and benchmarked, ran distributed computing, used old and power hungry hardware, or a combination of them all you would consider it.


----------



## cvaldes (Jul 13, 2021)

Sorry, I'm running current hardware: Ryzen 5900X & GeForce 3080. Today's silicon is far less opportunistic of overclocking. Much of the previous overclocking headroom is now built into the boost modes of modern silicon. Moreover I switched from AIOs to custom cooling loops a few months ago.

And no I'm not mining. If I want to invest $5000 in cryptocurrency, I'd rather buy $5000 of cryptocurrency rather than one or two GPUs or some custom ASIC. Mining cryptocurrency is for morons. It's like driving an Amazon delivery van. If you want to make money from Amazon, buy shares of AMZN stock. That's how almost all of the wealth of this planet is generated: investments not wages.

Better off investing thoughtfully, being patient and buying PC hardware at reasonable prices. I was patient enough to score a TUF Gaming 3080 OC card via Newegg Shuffle. I also scored the Ryzen 5900X from Amazon at MSRP. I'm not interested in awarding money to scalpers.

I care little for benchmarking other than its ability to help establish proper fan curves. I own gaming (Windows PC) computers, they are meant to run games, not benchmarks. As long as I know that the components are functioning normally, that's all that really counts.


----------



## claes (Jul 13, 2021)

I dunno, I’d say the majority of users run their fans at full speed. Even TPU members say as much followed by “and it’s dead silent,” even when running ippc fans and whatnot.


----------



## freeagent (Jul 13, 2021)

claes said:


> I dunno, I’d say the majority of users run their fans at full speed. Even TPU members say as much followed by “and it’s dead silent,” even when running ippc fans and whatnot.



Dude I have iPPC 3000s on my CPU, it is far from silent unless you are completely deaf. I have my PC in the basement, if I turn my fans up all the way I can hear it upstairs on the other side of the house. Most consumer fans are weak to me lol..


----------



## cvaldes (Jul 13, 2021)

Maybe you should spend the money on better home insulation and doors rather than PC fans. Or build a dedicated server room.

As I mentioned elsewhere, I have a Noctua NF-F14 industrialPPC-2000 PWM fan in my NXZT H1 case. But that fan never runs more than about 50% its peak rated speed.


----------



## freeagent (Jul 13, 2021)

cvaldes said:


> Maybe you should spend the money on better home insulation and doors rather than PC fans. Or build a dedicated server room.


----------



## Ominence (Jul 13, 2021)

80251 said:


> Delta FFB1424HHG 140x50mm vaneaxial fan at 2800 RPM produces more static pressure and CFM than the Noctua NF-A14 at 3000 RPM. 219.73 CFM vs. 159 CFM and 12.84mm-H2O vs. 10.52mm-H2O.


that's the advantage of its greater volumetric sweep even when offset partially with a disadvantage of lower rotational speed and no increment of swept area vs the NF-A14 3k.


----------



## The red spirit (Jul 13, 2021)

80251 said:


> I hate to disagree but the Delta FFB1424HHG 140x50mm vaneaxial fan at 2800 RPM produces more static pressure and CFM than the Noctua NF-A14 at 3000 RPM.  219.73 CFM vs. 159 CFM and 12.84mm-H2O vs. 10.52mm-H2O.


I just checked them out and that Delta isn't actually 50 mm thick. Well the whole thing is, but blades are 25mm thick, meanwhile the other half of it are air routing blades. Interesting. And for some reason Delta fan consumes whopping 17 watts, which is a lot. And when looking at spec sheet, you would think that Delta is obviously better, but it all is at cost of noise. Well, I don't really trust much spec sheets anymore, but at least on paper Delta is 54.5 dBA, meanwhile Noctua is 41.3 dBA. The difference should be huge. Anyway, it seems that it's possible to make thicker fan to be better at airflow. But even then, going thicker doesn't yield much gains. For 2 times thickness, you only get 20-30% static pressure and airflow. That's poor efficiency. Meanwhile, diameter increase would yield a lot more gains. And reason for that is simple. Sucked in air accelerates from hub to end of blades and thus at the end of blades, it is the fastest. Therefore, increasing thickness of fan and desiring more airflow would mean, that fan instead of working like a normal axial fan, now it would have to keep air longer on blades to accelerate it longer and thus change the angle of airflow. Unfortunately, that means more noise (because forcing air to to move at steeper than natural angle, is not aerodynamic and thus is noisy), and likely due to worse turbulence, airflow gains aren't big.



claes said:


> I dunno, I’d say the majority of users run their fans at full speed. Even TPU members say as much followed by “and it’s dead silent,” even when running ippc fans and whatnot.


I wonder how deaf average TPU user is. I'm deaf and I qualify for hearing aids, but even then fan noise is quite audible. My goal from cooling with fans is to stay close to the point of being audible and inaudible. Which for me would be 30-40 dB. I'm pretty sure that any healthy person would certainly hear a silent computer.


----------



## freeagent (Jul 13, 2021)

I’m watching old Top Gear on prime for my pc. I do hear it, but my sub is turned off volume is low and the pc is just a little background noise. Fans are all under 1k. If I fired up wcg right now I guarantee my kids in the next room would hear it, and I wouldn’t be able to hear top gear lol. It’s only loud when it has to work. Side note: I ran my 5600X the other day, it did not trigger the fans nearly as hard as 5900X. Not really a shocker.. it’s a puny hexacore


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## The red spirit (Jul 13, 2021)

freeagent said:


> I’m watching old Top Gear on prime for my pc. I do hear it, but my sub is turned off volume is low and the pc is just a little background noise. Fans are all under 1k. If I fired up wcg right now I guarantee my kids in the next room would hear it, and I wouldn’t be able to hear top gear lol. It’s only loud when it has to work. Side note: I ran my 5600X the other day, it did not trigger the fans nearly as hard as 5900X. Not really a shocker.. it’s a puny hexacore


That's just fancy way of saying that your computer is loud. If I was ever to claim that my computer is silent, then that means that it would be quiet under any load. Load up WCG and it's quiet, load up NicheHash and it's quiet. Load up RDR 2 and it's quiet. That's the essence of silent computer. People find it nice not having to listen to fan noise and many buy slow big fans, oversized radiators, oversized heatsinks, do other mods to make their systems like that. The main idea is that heatsinks should be very powerful already and fan should only aid natural convection. What you think is quiet (1k) isn't quiet, it's the upper limit of what I would tolerate in system. 600 rpm is quiet, 800 rpm is fine and 1000 rpm is still quiet, but just very borderline. I haven't really used any heatsink with fast fan in ages. Mugen 4 PCGH that I used earlier in my main PC had fans at fixed 800 rpms and it cooled well. In fact it cools so well, that even with fans removed, it can passively cool stock FX 6300. That would be i5 11600K equivalent today. That heatsink barely needed a fan, let alone two of them. My current heatsink (Scythe Choten) has a PWM fan, which goes from 300 rpm to 1200 rpm. My case fans currently are two 1000 rpm intakes and two 670 rpm exhausts. It's quite silent, but still little bit audible. And the result of this kind of computer building is that even at full load, I can hear Top Gear just fine. Meanwhile at idle, my system is stealthy.


----------



## freeagent (Jul 13, 2021)

I should also mention my pc is an htpc atm. Home schooling meant my kids use the desk for their pc. A little bit of noise doesn’t bother me in the slightest.

Some CPU’s throttle, some thrive. I know where mine sits


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## The red spirit (Jul 13, 2021)

freeagent said:


> I should also mention my pc is an htpc atm. Home schooling meant my kids use the desk for their pc. A little bit of noise doesn’t bother me in the slightest.
> 
> Some CPU’s throttle, some thrive. I know where mine sits


Eh, whatever. I have HTPC too and it's also quiet. Not as quiet as desktop, but not too bad.


----------



## freeagent (Jul 13, 2021)

Yes indeed, whatever. Also to note, I don't have to run my fans high at all. I can max my system using the silent fan profile all around lol. It just runs a few c warmer if I don't 

Boooossst


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## mtcn77 (Jul 13, 2021)

freeagent said:


> I should also mention my pc is an htpc atm. Home schooling meant my kids use the desk for their pc. A little bit of noise doesn’t bother me in the slightest.
> 
> Some CPU’s throttle, some thrive. I know where mine sits


We are fudging around, but an exhaust fan shroud attached to the cpu heatsink (thermalright sells them) can drop case internals by 10°C. Come to think of it, it is no insignificant feat to brush aside.


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## The red spirit (Jul 13, 2021)

mtcn77 said:


> We are fudging around, but an exhaust fan shroud attached to the cpu heatsink (thermalright sells them) can drop case internals by 10°C. Come to think of it, it is no insignificant feat to brush aside.


The key being sometimes. I'm pretty sure that my downdraft cooler indeed makes upper case internals cooler (particularly VRMs).


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## mtcn77 (Jul 13, 2021)

The red spirit said:


> The key being sometimes. I'm pretty sure that my downdraft cooler indeed makes upper case internals cooler (particularly VRMs).


Best use scenario is ducting all the heatsinks to contain their heat soaked exit spill over in a uniform channel. Linus tested this with the original Cosmos case that came with an air duct for the gpu. It dropped the gpu temperature by 20°C and slowed that blower to utter silence, but somehow that video got removed, or I cannot find it any more.
Anyway, as we have discussed and in the video above about pumps, the fan's efficiency drops by the square of distance from it, so every bit counts to channel the air in the exhaust path and not have reciprocated heat buildup due to air stall.


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## freeagent (Jul 13, 2021)

mtcn77 said:


> We are fudging around, but an exhaust fan shroud attached to the cpu heatsink (thermalright sells them) can drop case internals by 10°C. Come to think of it, it is no insignificant feat to brush aside.


Oh yeah, you are talking about the Thermalright duct? That was for using your Le Grand macho RT or similar in semi passive mode. Its a neat idea. It would probably do well in a system that is 2d orientated. Or maybe something like an HTPC..


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## The red spirit (Jul 13, 2021)

mtcn77 said:


> Best use scenario is ducting all the heatsinks to contain their heat soaked exit spill over in a uniform channel. Linus tested this with the original Cosmos case that came with an air duct for the gpu. It dropped the gpu temperature by 20°C and slowed that blower to utter silence, but somehow that video got removed, or I cannot find it any more.


While this sure does work sometimes, I doubt it will work often. And the reason for that is simple. Ducting, if not aerodynamic, would require lots of static pressure to work and since not all cases have much empty space, ducting might be counter productive. But otherwise, ducting isn't new concept and has been proven to work quite well. I don't know why there aren't any proper aftermarket ducts for computers.


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## mtcn77 (Jul 13, 2021)

The red spirit said:


> While this sure does work sometimes, I doubt it will work often. And the reason for that is simple. Ducting, if not aerodynamic, would require lots of static pressure to work and since not all cases have much empty space, ducting might be counter productive. But otherwise, ducting isn't new concept and has been proven to work quite well. I don't know why there aren't any proper aftermarket ducts for computers.


Well, you can see in the practical engineering video about pumps, eventhough they do work at a distance, they do inversely less work(pressure wise). Carving the shortest path to the nearest exhaust becomes important.


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## formula383 (Jul 13, 2021)

The red spirit said:


> I think that bigger downfall of that post is that fan spec data collection methods are undisclosed and they are likely aren't accurate. I dunno, I start to feel that generic 7 blader is one of the best fan shapes and everything else is trying to deviate from it for deviation's sake.
> 
> 
> If you decide to do any testing, please test generic 7 blade fan.


Welcome to the real world kid 

You are most likely correct. And that's just the nature of the free free market and corporations. Make all the money you can while spending next to nothing to do so.
But i feel the truth is some fans are better than others. the question is will they be better for your specific application and are they worth the cost.
If you want to really know something is right, you must do it yourself. Else you will always have the what if in your mind. The old say go's "if you want something done right you gotta do it your self" i would like to think everyone has heard this but in todays world i'm pretty sure many have not.

I guess what i'm saying is until you get your hands on these differnt fans for your self and conduct the test you want to do. you might always have questions.

Have you seen the Aero Shark fans before?



I used 4 of these on a friends build he had a 420mm rad that had really low FPI and was pretty thick. These things were pretty quiet at full speed but they worked so well on his 2600k and 7950x even with a solid OC we just left the fans on something like 70~80% speed that thing was dead silent and the temps were insanely low(maybe it was not dead silent it was years ago but i know it was very quiet, i still have one of these fans in my other pc as exhaust and its running full speed and i can barely hear it). Granted this rad was mounted to the top of the pc out side of the case and had almost no obstructions other than the fan grills we put on top. Really turned out to be a sweet setup.

I was very surprised how well these fans did for low pressure air flow. at first look i thought they would be terrible and they probably would be on a high fpi rad or anything restrictive. kinda neat looking and unique fan design tho.


----------



## FireFox (Jul 13, 2021)

The red spirit said:


> I wonder how deaf average TPU user is. I'm deaf and I qualify for hearing aids, but even then fan noise is quite audible. My goal from cooling with fans is to stay close to the point of being audible and inaudible. Which for me would be 30-40 dB. I'm pretty sure that any healthy person would certainly hear a silent computer.


In all the previous PC I've owned before i used to run the fans at max speed, i remember when i had the *NF-F12 PPC 2000 PWM *running at 2000rpm, they were loud but because i wore Headphones it never bothered me, since i work at the Airport and i have to wear Hearing protection/Ear Muffs for almost 8 hours everyday due to the Airplanes now my hearing has become sensitive and noises bothers me a lot.
On my current Build i run the fans at 600Rpm/700Rpm but that's just if the room temp isn't too high otherwise if it is like a few days ago 31c then i need to increase the Rpm, the max speed i run the fans is 1150RPM because they are pretty quiet.


The red spirit said:


> My goal from cooling with fans is to stay close to the point of being audible and inaudible. Which for me would be 30-40 dB. I'm pretty sure that any healthy person would certainly hear a silent computer.


from 600rpm up to 800rpm my Build is almost inaudible, from 900rpm and above the only thing i hear it is the damn pump


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## The red spirit (Jul 13, 2021)

formula383 said:


> You are most likely correct. And that's just the nature of the free free market and corporations. Make all the money you can while spending next to nothing to do so.
> But i feel the truth is some fans are better than others.


I just think that some fans just look really cool. I really love the look of Silverstone Air Penetrators with fat translucent blue blades. Or Noiseblocker Black Silents with basic 7 blade design, but nice purple translucent blades:






I have one myself and they actually look just as good irl. I have a feeling that they would look good in smoked tempered glass case.




formula383 said:


> the question is will they be better for your specific application and are they worth the cost.
> If you want to really know something is right, you must do it yourself. Else you will always have the what if in your mind. The old say go's "if you want something done right you gotta do it your self" i would like to think everyone has heard this but in todays world i'm pretty sure many have not.
> 
> I guess what i'm saying is until you get your hands on these different fans for your self and conduct the test you want to do. you might always have questions.


Well, I have bunch of random fans myself. Most of them aren't too different, but I noticed that Silencio fans just don't seem to move as much air. After reading shit ton of fans tests and reviews, I came to conclusions that blade shape barely matters. That's a bit anti-climatic in this thread, but that's the truth so far.



formula383 said:


> Have you seen the Aero Shark fans before?


Yes, they look pretty cool. They kinda remind me of Enermax T.B. Silence fans with bat wings:





I have 80mm version myself and they are quite good. But they are abysmal at generating pressure. Even worse than Xilence Redwings Performance C.


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## formula383 (Jul 13, 2021)

There are bad fans around. but i think over the years things have gotten better for all quality of fans. little aspects for lowering noise have been included in almost all fan designs of today. 20 years ago might have been a completely different story. So i guess your lucky today you can find pretty OK fans with just about anything on the market. some of that might be in thanks to the internet allowing people to voice and share there opinions and findings. Other reasons might include patents expiring and tooling (molds) being reused for cheaper fans as new designs are being made. That and technology keeps getting more refined so making quality parts becomes less difficult and less costly to do.

you have heard? "you get more miles out of cheap pair of sneakers" this i think is very true in fans. However some fans do use better quality plastics that do cost more. and they even might have slightly better air flow with less noise at the same time. Or maybe more so the tone of the noise that is less bothersome to our ears. I have really enjoyed using "cougar" fans they often can be found on sale and they are pretty good quality. I also like the orange color blades too  I think they make black ones if you dont like the orange but yea been pretty happy with them for the price they are very good fans. i think the first ones i bought were around $7~8 each but that was years ago. now i feel like if you can get 120mm for around $13~15 they are well worth it.



i think the color is slightly off in this photo but at least you can see the style of it.

PS they do make a few different types so pay close attention to what type you are buying. The last ones i got are CF-V 12HP 1500rpm. They do make noise but i think its more the air flow making the noise rather than the fan it self. At any rate they are worth giving a shot imho.


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## The red spirit (Jul 13, 2021)

formula383 said:


> I also like the orange color blades too  I think they make black ones if you dont like the orange but yea been pretty happy with them for the price they are very good fans.


I probably like colored version more than black version. But then again, in the past I have bought some bright green Akasa Vegas fans and put them on Cooler Master K280 case. They looked great through mesh and air filter. That looked a bit like starry sky with green dots, lovely effect



formula383 said:


> i think the first ones i bought were around $7~8 each but that was years ago. now i feel like if you can get 120mm for around $13~15 they are well worth it.


For me locally, Cougar products aren't really available or cheap. The clear budget winner is Arctic P12 fans, due to their sub 7 Euro cost. In similar price bracket there are Thermaltake Pure 12, Zalman F2 Plus, Silentium Zephyr fans. For less than 9 Euros you can get Scythe Slipstream, Bitfenix Spectre, Silverstone FN121-P-L, Silentium Sigma Pro fans. Pretty good, but still visually bland. And basically all other fans are at under 15 Euros. And some fans are at over 20 Euros for a single fan (mostly Noctuas). But deals depend on store. Other stores have cheap Cooler Master SickleFlow, Deepcool RF120, Xilence Redwing fans for cheap. Some fans are sold for less than 4 Euros. Really no point in paying tithe for "premium" fans (they aren't all that premium, plenty of tests show that they are not really better and sometimes poor in comparison to others).


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## 80251 (Jul 13, 2021)

The red spirit said:


> I just checked them out and that Delta isn't actually 50 mm thick. Well the whole thing is, but blades are 25mm thick, meanwhile the other half of it are air routing blades. Interesting. And for some reason Delta fan consumes whopping 17 watts, which is a lot. And when looking at spec sheet, you would think that Delta is obviously better, but it all is at cost of noise. Well, I don't really trust much spec sheets anymore, but at least on paper Delta is 54.5 dBA, meanwhile Noctua is 41.3 dBA. The difference should be huge. Anyway, it seems that it's possible to make thicker fan to be better at airflow. But even then, going thicker doesn't yield much gains. For 2 times thickness, you only get 20-30% static pressure and airflow. That's poor efficiency. Meanwhile, diameter increase would yield a lot more gains. And reason for that is simple. Sucked in air accelerates from hub to end of blades and thus at the end of blades, it is the fastest. Therefore, increasing thickness of fan and desiring more airflow would mean, that fan instead of working like a normal axial fan, now it would have to keep air longer on blades to accelerate it longer and thus change the angle of airflow. Unfortunately, that means more noise (because forcing air to to move at steeper than natural angle, is not aerodynamic and thus is noisy), and likely due to worse turbulence, airflow gains aren't big.
> 
> 
> I wonder how deaf average TPU user is. I'm deaf and I qualify for hearing aids, but even then fan noise is quite audible. My goal from cooling with fans is to stay close to the point of being audible and inaudible. Which for me would be 30-40 dB. I'm pretty sure that any healthy person would certainly hear a silent computer.


Delta publishes the methodology and equipment used by which they arrive at their figures for each fan. They produce far more fans for far more applications than Noctua. There ARE standards for measuring fan performance metrics published by international standards bodies as well as for the USA alone.

If we were to lower the Delta's 140x50mm RPM level so that it matched the noctua's CFM and static pressure what would the dbA levels be then? Insignificantly different?


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## The red spirit (Jul 13, 2021)

80251 said:


> If we were to lower the Delta's 140x50mm RPM level so that it matched the noctua's CFM and static pressure what would the dbA levels be then? Insignificantly different?


Granted that spec sheets say truth, I would say that delta would be a little bit louder then. But only by 3 dBA or less.


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## mtcn77 (Jul 13, 2021)

The red spirit said:


> Granted that spec sheets say truth, I would say that delta would be a little bit louder then. But only by 3 dBA or less.


Those vanes don't operate quietly.


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## Deleted member 212040 (Jul 14, 2021)

Meanwhile I just run Silent Wings 3 140mm PWM all across the board at 1000 RPM and they do the job well while being quiet. Set it and forget it.

No need to overthink all of this. Dust? Unwinnable battle, get a blower and dust your PC out once in a while.


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## mtcn77 (Jul 14, 2021)

Emily said:


> Meanwhile I just run Silent Wings 3 140mm PWM all across the board at 1000 RPM and they do the job well while being quiet. Set it and forget it.
> 
> No need to overthink all of this. Dust? Unwinnable battle, get a blower and dust your PC out once in a while.


Silent Wing 3's are top grade fans according to hardware.info though. You are oversimplifying the debate by virtue of settling the problem.


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## Deleted member 212040 (Jul 14, 2021)

mtcn77 said:


> Silent Wing 3's are top grade fans according to hardware.info though. You are oversimplifying the debate by virtue of settling the problem.


Top grade fans? I recall them being called shitty by pretty much everyone


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## mtcn77 (Jul 14, 2021)

Emily said:


> Top grade fans? I recall them being called shitty by pretty much everyone


Everyone, except me. Don't worry about stuffies.


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## Deleted member 212040 (Jul 14, 2021)

Well count me in too because I love them lol


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## mtcn77 (Jul 14, 2021)

Emily said:


> Well count me in too because I love them lol


I was looking through past review material, but since they don't overlay different methodologies together(there are 2 charts for 2019 tests, 1 for 2017, 1 for 2014) it becomes hard comparing them. While nfa12x25 are respectable, I bet they aren't the best. I couldn't figure how I listed the best in previous reviews though, maybe because I'm trying to overlay the new noctua review...


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## The red spirit (Jul 14, 2021)

mtcn77 said:


> I was loking through past review material, but since they don't overlay different methodologies together it becomes hard comparing them. While nfa12x25 are respectable, I bet they aren't the best. I couldn't figurr how I listed the best in previous reviews though, maybe because I'm trying to overlay the new noctua review...


I have watched a lot of reviews and yes, Noctua isn't the best. Reduxes seemingly perform even worse. Depending on review, winner changes, but I have seen Arctic P12, Scythe Kaze Flex, NoiseBlocker Multiframe being the best. Noctua either is average or slightly above average. Always on the bottom is Corsair and Be Quiet's Shadow Wings.


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## freeagent (Jul 14, 2021)

I've been looking at the Redux 1700s because they are cheap.. literally half the cost of SW3's. Probably quieter than my old Panaflos. Only 70cfm though.. kind of a bummer. Next step up is iPPC 2000s. Bah. Consumer fans =


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## Deleted member 212040 (Jul 14, 2021)

I don't wanna hear about Arctic P12s, P14, Pwhatevers ever again. Bought a 5 pack, some P14s as well, and all of them had the worst motor noise ever.

My NF-A12x25s on my cooler and the Silent Wings 3 I use as case fans are so quiet that the coil noise in my PC is more audible.



freeagent said:


> Only 70cfm though..


I'm over here trudging along with 60 cfm because I've found that anything above 1000 rpm on my 140mm fans make 0 difference to cooling but a lot of difference to my hearing.


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## mtcn77 (Jul 14, 2021)

Okay, it might be a noob moment, but I just figured Noctua's "FLX" attributed fans are their free flow fans... you know what to do for radiator fans, that goes without saying.

PS: while it may be not correlatable, they have tested two different sets of the same test at different dBA values - don't ask me why.
Noctuas are on the half ordinal, while the rest are on the full ordinal. I have never seen such a stupid methodology baitswitch, but it is what it is...


----------



## claes (Jul 14, 2021)

I’m wondering who you all trust with fan reviews?  I don’t trust any of the YouTube reviewers I’ve encountered, and only a handful of written reviewers have what I would consider to be a decent test methodology.

My admittedly short list:
Silent PC Review (defunct)
Ehume/overclockers.com (defunct)
@VSG/thermalbench/TPU (not sure if we’ll be seeing any fan reviews at TPU but TB.com was great)

Any others people would recommend?

Edit: hardware.info seems okay but they seem to change methods without notification. I remember liking some German site but I don’t remember which, and don’t think they’ve done fan reviews for awhile. PCper used to be okay but I haven’t kept up with them either.


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## mtcn77 (Jul 14, 2021)

claes said:


> Ehume/overclockers.com (defunct)


Haha, he runs vortez.net. He isn't a rookie.
Again, this is the ~7v(not exact since they didn't crossmatch the old dBA test to it) air flow list. Since Noctuas and Scythe Kaze are only tested among themselves, they are DNF, but stronger than the rest.
We still don't know what regular fans would do as sp fans for limitation of methodology.
30dBA-cfm ordered


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## VSG (Jul 14, 2021)

claes said:


> I’m wondering who you all trust with fan reviews?  I don’t trust any of the YouTube reviewers I’ve encountered, and only a handful of written reviewers have what I would consider to be a decent test methodology.
> 
> My admittedly short list:
> Silent PC Review (defunct)
> ...


I've been doing fan reviews here as well, just search for "fan" or similar in the reviews section: https://www.techpowerup.com/review/


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## freeagent (Jul 14, 2021)

Emily said:


> 'm over here trudging along with 60 cfm because I've found that anything above 1000 rpm on my 140mm fans make 0 difference to cooling but a lot of difference to my hearing.




I know, one of my Panaflos has a low frequency rumble at higher RPMs. They have been running since 2006. They don't spin as freely as my other fans, so I will replace them all at once. They don't owe me a thing.. My iPPC are pretty decent. I barely heard them with my 5600, but with my 5900 they sound like they are angry that it even thought of making heat. Ehume is a pretty good guy, for sure he knows what he is talking about. I butted heads with him once a few years ago and I still feel bad about it because I wouldn't back down, and I probably should have. Young guys eh.. think they know it all.

Some of those guys still float around the forums..


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## The red spirit (Jul 14, 2021)

claes said:


> I’m wondering who you all trust with fan reviews?


To be honest, there's no point in doing that. Generic 7/9 blader is pretty much the best shape of fan. There really aren't fans that are truly bad and fans that are way above others. They are all the variation of same or similar thing. Besides from catching some poorly performing fans, fan reviews are pretty much pointless now. It's just like power supplies. You could buy a clearly dangerous unit in the past, but today, pretty much anything is fine and there's not much point in paying more than you should.


----------



## Shrek (Jul 14, 2021)

Fans tend to use a prime number of blades to avoid harmonics, so 7 might be better than 9; interesting that house fans tend to be 3 or 5 bladed, although I have one 4 bladed unit.

I remain of the opinion that the bearing is important, something that isn't really tested in reviews; ball bearings can get noisy with age.


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## mtcn77 (Jul 14, 2021)

Andy Shiekh said:


> Fans tend to use a prime number of blades to avoid harmonics,


12cm Noiseblocker eLoops have the rotor stator ring which enable a 6 bladed design. I would say they do well.



The red spirit said:


> They aren't any more noisier than any other fans. Come on, it's Scythe. They are specializing in quiet and powerful cooling solutions far more than other brands. Anyway, if yo uare interested in Fuma 2, you have to watch these two videos, they explain everything:
> 
> 
> 
> ...


I think we would get better results from the counter rotating fans on the Fuma 2, had MajorHardware tested them on the same slot. He tested with an extra push-pull-pull triple fan setup, yet he never considered push-push-pull like optimum tech did. Long story short, at same noise corrected performance, this enables 0.5 degrees better cooling even not considering counter rotating impellers. Which was my idea for gradual air acceleration for high laminar flow at even less axial pressure gradient.


----------



## HTC (Jul 15, 2021)

Andy Shiekh said:


> Fans tend to use a prime number of blades to avoid harmonics, so 7 might be better than 9; interesting that house fans tend to be 3 or 5 bladed, although I have one 4 bladed unit.
> 
> *I remain of the opinion that the bearing is important, something that isn't really tested in reviews; ball bearings can get noisy with age.*



As someone who works @ a ball bearing manufacturing factory, i can tell you that ALL honed bearings (bearings where their rings are polished) are tested for their noise levels and they have tolerances for low, mid and high frequencies.

Noctua MAY just require tighter tolerances of the bearings they use which results in better noise levels: this DOES MAKE the bearings A LOT MORE PRICEY as the quality control is different.


----------



## Shrek (Jul 15, 2021)

I meant as they age... not as they are new.


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## HTC (Jul 15, 2021)

Andy Shiekh said:


> I meant as they age... not as they are new.



I wouldn't believe how many ball bearings go to scrap PER DAY because they fail noise testing, and that's THE DAY THEY ARE ASSEMBLED.

As long as it's protected (the covers) and not damaged in some way, a ball bearing WILL perform correctly for many MANY years.


----------



## The red spirit (Jul 15, 2021)

mtcn77 said:


> I think we would get better results from the counter rotating fans on the Fuma 2, had MajorHardware tested them on the same slot. He tested with an extra push-pull-pull triple fan setup, yet he never considered push-push-pull like optimum tech did. Long story short, at same noise corrected performance, this enables 0.5 degrees better cooling even not considering counter rotating impellers. Which was my idea for gradual air acceleration for high laminar flow at even less axial pressure gradient.


I doubt it would make a difference. He said that anything beyond stock config barely does anything differently, which would mean that Fuma 2's heatsink isn't very restrictive and there's no need for more static pressure. Instead, maybe higher air velocity may help.



HTC said:


> I wouldn't believe how many ball bearings go to scrap PER DAY because they fail noise testing, and that's THE DAY THEY ARE ASSEMBLED.
> 
> As long as it's protected (the covers) and not damaged in some way, a ball bearing WILL perform correctly for many MANY years.


By correctly, do you mean that they won't get any louder?


----------



## 80-watt Hamster (Jul 15, 2021)

Emily said:


> I don't wanna hear about Arctic P12s, P14, Pwhatevers ever again. Bought a 5 pack, some P14s as well, and all of them had the worst motor noise ever.
> 
> My NF-A12x25s on my cooler and the Silent Wings 3 I use as case fans are so quiet that the coil noise in my PC is more audible.
> 
> ...



I just bought a P12 to see what all the fuss is about.  Not impressed.  Motor noise isn't great as you said, and mine is noticeably out of balance.


----------



## HTC (Jul 15, 2021)

The red spirit said:


> I doubt it would make a difference. He said that anything beyond stock config barely does anything differently, which would mean that Fuma 2's heatsink isn't very restrictive and there's no need for more static pressure. Instead, maybe higher air velocity may help.
> 
> 
> *By correctly, do you mean that they won't get any louder?*



*Likely*, yes. Unless ofc affected by external forces during it's lifespan.

For an applicable example, say you use a can of compressed air to clean your fans and, in so doing, you make the fan spin *@ a much higher than rated* speed: this *MAY* cause problems for the bearing because it was never designed to work @ such speed.


----------



## The red spirit (Jul 15, 2021)

80-watt Hamster said:


> I just bought a P12 to see what all the fuss is about.  Not impressed.  Motor noise isn't great as you said, and mine is noticeably out of balance.


Oh well... That's disappointing for sure, but from all data they seem to be good and sometimes chart topping fans. I have bought some other Arctic stuff and its quite solid, fan being out of balance seems like manufacturing defect. I hope that you can RMA them.



HTC said:


> *Likely*, yes. Unless ofc affected by external forces during it's lifespan.
> 
> For an applicable example: say you use a can of compressed air to clean your fans and, in so doing, you make the fan spin *@ a much higher than rated* speed. This MAY cause problems for the bearing because it was never designed to work @ such speed.


Out of curiosity, what can happen to bearing if it is spun too fast?


----------



## HTC (Jul 15, 2021)

The red spirit said:


> Oh well... That's disappointing for sure, but from all data they seem to be good and sometimes chart topping fans. I have bought some other Arctic stuff and its quite solid, fan being out of balance seems like manufacturing defect. I hope that you can RMA them.
> 
> 
> *Out of curiosity, what can happen to bearing if it is spun too fast?*



I'm not entirely sure because i work in the manufacturing rings section and not in the assembly quality control section, though i did work in the bearing's rings assembly in the past (placed the spheres or the cages in the bearings).

Cage picture:







Think of it this way: what happens when you rev your car's engine OVER the red line's max?


----------



## The red spirit (Jul 15, 2021)

HTC said:


> I'm not entirely sure because i work in the manufacturing rings section and not in the assembly quality control section, though i did work in the bearing's rings assembly in the past (placed the spheres or the cages in the bearings).
> 
> Think of it this way: what happens when you rev your car's engine until the red line's max?


I dunno, because I don't drive, but technically it should heat up beyond manufacturer engineered limit (sorry, I'm talking about overreving, not redlining). Depending on how bad overheating is, it can bend engine's internal components and thus ruin the engine. Due to high pressure inside cylinders, if something isn't able to contain it there, engine will "blow" up. But then again, it depends on engine and on particular weak spots of engine and of left tolerance by manufacturer. Some cards rev very high without problems. Honda S2000 or EK9 R, can rev over 8000 rpm without problem. Some cars have rotary engines and those usually are designed to be revved a lot and for those cars it's advisable to rev them one per month, so that apex seals don't get flooded. Last rotary car, RX8 can rev to over 9000 rpm and it's totally fine with that, also it sound really nice at those revs. Motorcycles and F1 cars can rev a lot more.

Anyway, fans aren't cars and there's not much heat made by them. Also, I'm pretty sure that exactly the same bearings are used for quiet and faster fan models, so they probably can handle going over spec for a while (when vacuuming them for example). The bigger problem is that if you spin them fast, they become electricity generators and do start to send electricity the other way. I have seen this myself. If I blow hard on CM Blue LED fan, LEDs light up. Certainly not much , just a little bit, but maybe I generated 6 volts or so.


----------



## HTC (Jul 15, 2021)

The red spirit said:


> I dunno, because I don't drive, but technically it should heat up beyond manufacturer engineered limit (sorry, I'm talking about overreving, not redlining). Depending on how bad overheating is, it can bend engine's internal components and thus ruin the engine. Due to high pressure inside cylinders, if something isn't able to contain it there, engine will "blow" up. But then again, it depends on engine and on particular weak spots of engine and of left tolerance by manufacturer. Some cards rev very high without problems. Honda S2000 or EK9 R, can rev over 8000 rpm without problem. Some cars have rotary engines and those usually are designed to be revved a lot and for those cars it's advisable to rev them one per month, so that apex seals don't get flooded. Last rotary car, RX8 can rev to over 9000 rpm and it's totally fine with that, also it sound really nice at those revs. Motorcycles and F1 cars can rev a lot more.
> 
> Anyway, fans aren't cars and there's not much heat made by them. Also, I'm pretty sure that exactly the same bearings are used for quiet and faster fan models, so they probably can handle going over spec for a while (when vacuuming them for example). The bigger problem is that if you spin them fast, they become electricity generators and do start to send electricity the other way. I have seen this myself. If I blow hard on CM Blue LED fan, LEDs light up. Certainly not much , just a little bit, but maybe I generated 6 volts or so.


I edited my previous post but you quoted it before i did: i mean OVER the red line's max and NOT to the red line's max. I don't drive either.

Also, ball bearings DO heat up if you rotate them @ high speed, EVEN IF within speed tolerances: more so if outside speed tolerances. As with everything, *use something incorrectly and it may break prematurely*.


----------



## claes (Jul 15, 2021)

mtcn77 said:


> Haha, he runs vortez.net. He isn't a rookie.


Are you sure? Looks like the editor is David Mitchelson and the (weird) fan reviews seem to be done by a Matthew Hodgson.


VSG said:


> I've been doing fan reviews here as well, just search for "fan" or similar in the reviews section: https://www.techpowerup.com/review/


Oh yay great I hadn’t noticed 


The red spirit said:


> To be honest, there's no point in doing that. Generic 7/9 blader is pretty much the best shape of fan. There really aren't fans that are truly bad and fans that are way above others. They are all the variation of same or similar thing. Besides from catching some poorly performing fans, fan reviews are pretty much pointless now. It's just like power supplies. You could buy a clearly dangerous unit in the past, but today, pretty much anything is fine and there's not much point in paying more than you should.


Hard disagree — why’d you make this thread lol  As a noise freak I miss SPCR dearly, and, like I had said before, most of these fan reviews have poor test methods that yield wacky results. Does a degree or two make that much of a difference? Not really. But 2dB does, as does motor noise, noise when faced with impedance, performance in free-air vs a radiator etc


----------



## Shrek (Jul 15, 2021)

When hard drives used ball bearings, before fluid dynamic bearings, they could get VERY noisy with wear.

Hard drive ball bearing sound comparison - Bing video

and one can be sure this is not due to over revving


----------



## The red spirit (Jul 15, 2021)

HTC said:


> Also, ball bearings DO heat up if you rotate them @ high speed, EVEN IF within speed tolerances: more so if outside speed tolerances. As with everything, *use something incorrectly and it may break prematurely*.


Sure, but I'm afraid that it would take a lot of incorrect overreving of fans to actually damage them.


----------



## HTC (Jul 15, 2021)

The red spirit said:


> Sure, but I'm afraid that it would take a lot of incorrect overreving of fans to actually damage them.



Right away, probably not: over time, likely.


----------



## The red spirit (Jul 15, 2021)

claes said:


> Hard disagree — why’d you make this thread lol  As a noise freak I miss SPCR dearly, and, like I had said before, most of these fan reviews have poor test methods that yield wacky results. Does a degree or two make that much of a difference? Not really. But 2dB does, as does motor noise, noise when faced with impedance, performance in free-air vs a radiator etc


I read and watched tons of reviews and sorry, but almost all fans are pretty much the same in terms of performance and on top of that, if some "real world" testing is done, that will distort data, due to to certain fans being slightly better or slightly worse for certain conditions. Those people aren't aware of pressure/cfm curves it seems.

Even TPU reviews indicate that all fans are pretty much the same with some minor differences (although, their methodology is quite poor).



HTC said:


> Right away, probably not: over time, likely.


I don't think that vacuuming or using air can, really counts as over time.


----------



## claes (Jul 15, 2021)

I don’t think you read or understood my post 

Some fans are objectively better performers, some have lower variance between samples, all have different noise characteristics, etc. Joe YouTube might not notice (looking forward to GN though) but I sure do


----------



## The red spirit (Jul 15, 2021)

claes said:


> I don’t think you read or understood my post
> 
> Some fans are objectively better performers, some have lower variance between samples, all have different noise characteristics, etc. Joe YouTube might not notice (looking forward to GN though) but I sure do


Objectively better by what? 5%? That stuff means nothing.


----------



## freeagent (Jul 15, 2021)

Im sure set RPM limits are due to wear. Go over the limit and the wear pattern changes because of velocity. I lost a nice TY-147A due to over revs, but it is an FDB bearing. My double ball TY-143 had the same annoying high pitch for the 3 years it lived with me. I believe it died because of over revs too. But the bearing was fine, the board is cooked and wont rev over 650. My TY-147A wont rev over 250 and it feels like shit.

Edit:

So this is why I am changing my case fans, I am moving too much air.


----------



## HTC (Jul 15, 2021)

The red spirit said:


> I read and watched tons of reviews and sorry, but almost all fans are pretty much the same in terms of performance and on top of that, if some "real world" testing is done, that will distort data, due to to certain fans being slightly better or slightly worse for certain conditions. Those people aren't aware of pressure/cfm curves it seems.
> 
> Even TPU reviews indicate that all fans are pretty much the same with some minor differences (although, their methodology is quite poor).
> 
> ...



You misunderstood: it MAY shorten it's life span right away, depending on how much more than rated speed we're talking about. *More likely though*, the fan will work and *APPEAR to be normal* for some time but you'll begin to notice problems sooner than you would otherwise, and that's the part that takes time. In essence, instead of 6 years (as per Noctua's warranty), may last 5 or less, depending on the "out-of-spec treatment" it got.


----------



## 80251 (Jul 15, 2021)

mtcn77 said:


> 12cm Noiseblocker eLoops have the rotor stator ring which enable a 6 bladed design. I would say they do well.





mtcn77 said:


> I think we would get better results from the counter rotating fans on the Fuma 2, had MajorHardware tested them on the same slot. He tested with an extra push-pull-pull triple fan setup, yet he never considered push-push-pull like optimum tech did. Long story short, at same noise corrected performance, this enables 0.5 degrees better cooling even not considering counter rotating impellers. Which was my idea for gradual air acceleration for high laminar flow at even less axial pressure gradient.


Wouldn't the fact the air has to flow through the radiator end up straightening out the airflow so that contra-rotating fans would be irrelevant?


----------



## VSG (Jul 15, 2021)

The red spirit said:


> Even TPU reviews indicate that all fans are pretty much the same with some minor differences (although, their methodology is quite poor).


Why is my methodology quite poor?


----------



## mtcn77 (Jul 15, 2021)

80251 said:


> Wouldn't the fact the air has to flow through the radiator end up straightening out the airflow so that contra-rotating fans would be irrelevant?


Says it word for word in the majorhardware review, too. It still works good with smoke test, though.

My point was trail edge separation that could be solved by two step acceleration of air. AF fans apply less pressure, sp fans more.

I know I said the opposite case previously before, but since stall is generated by pressure, dropping the pressure gradient at the second sp fan by a primary af fan could either dampen, or accentuate its noise pattern, depending on which edge the sound is generated from(accentuated at the front if it stems from too much charge at the compression side, or dampened at the trail if happening due to trail separation).
If majorhardware can do it, so can we.



VSG said:


> Why is my methodology quite poor?


You know how things are. Your reviews aren't rgb flaired.


----------



## formula383 (Jul 15, 2021)

HTC said:


> I'm not entirely sure because i work in the manufacturing rings section and not in the assembly quality control section, though i did work in the bearing's rings assembly in the past (placed the spheres or the cages in the bearings).
> 
> Cage picture:
> 
> ...


Thats not at all the same thing. Engines use fluid bearings, no balls in them. the valve train is what takes a shit first, and then possibly the pistions will seize as the oil gets too hot and gets burned off the cylinder walls.


----------



## The red spirit (Jul 15, 2021)

VSG said:


> Why is my methodology quite poor?


There are no tests done without radiator and using certain radiator may bias results, due to fitting that specific radiator better. I think that that particular Silverstone fan, which tops charts shouldn't be included in 120mm comparison, as it is 140mm fan with 120mm mounting holes. Which is quite unfair and it may not really fit into 120 mountings everywhere. For example, 240mm rad. It would be nice to see CFM/dBA chart too, which I feel is very relevant. Also there's no pure static pressure test, I guess radiator works as real world test, but I'm not too sure.


----------



## mtcn77 (Jul 15, 2021)

The red spirit said:


> Also there's no pure static pressure test, I guess radiator works as real world test, but I'm not too sure.


Pressure test can be cheated by running louder.


----------



## The red spirit (Jul 15, 2021)

mtcn77 said:


> Pressure test can be cheated by running louder.


Then dBA normalized static pressure test.


----------



## mtcn77 (Jul 15, 2021)

The red spirit said:


> Then dBA normalized static pressure test.


*that is moving the goalpost.*
Don't censure someone else not recognising your own fault. Radiator tests should be the industry standard, not the other way around.


----------



## The red spirit (Jul 15, 2021)

mtcn77 said:


> *that is moving the goalpost.*
> Don't censure someone else not recognising your own fault. Radiator tests should be the industry standard, not the other way around.


Why? Most people don't use them. I built quite a bit of systems and only once with radiator.


----------



## mtcn77 (Jul 15, 2021)

The red spirit said:


> Why? Most people don't use them. I built quite a bit of systems and only once with radiator.


You aren't doing that for water cooling, rather to demarcate the fan's properties.


----------



## The red spirit (Jul 15, 2021)

mtcn77 said:


> You aren't doing that for water cooling, rather to demarcate the fan's properties.


Fan properties wouldn't be the same if you weren't water cooling.


----------



## VSG (Jul 15, 2021)

The red spirit said:


> Fan properties wouldn't be the same if you weren't water cooling.


Exactly. This is why I mention as much in my fan reviews which are part of the water cooling review category here


----------



## The red spirit (Jul 15, 2021)

VSG said:


> Exactly. This is why I mention as much in my fan reviews which are part of the water cooling review category here


I think that the most practical and easiest to implement change would be to add CFM per dBA graph. No need to collect new data, just do some calculations and reader gets some nice very relevant data. That radiator test is actually a bit genius, due to how it tests pressure and air velocity as all once, but obviously it doesn't give lots of data if fan is used in other conditions.


----------



## VSG (Jul 15, 2021)

The red spirit said:


> I think that the most practical and easiest to implement change would be to add CFM per dBA graph. No need to collect new data, just do some calculations and reader gets some nice very relevant data. That radiator test is actually a bit genius, due to how it tests pressure and air velocity as all once, but obviously it doesn't give lots of data if fan is used in other conditions.


I did that before elsewhere and it quickly became a nightmare with overlapping graphs. This is the most accessible approach at this time.


----------



## The red spirit (Jul 15, 2021)

VSG said:


> I did that before elsewhere and it quickly became a nightmare with overlapping graphs. This is the most accessible approach at this time.


Could you link me an example of that?


----------



## formula383 (Jul 15, 2021)

Each fan has a type of use, so if i was to make a review those fans would be tested in there specific use case. But again most fans are pretty similar for most use cases. so not really a huge deal imho.

And you could always throw in other use cases mix matching for fun and depth too. (you know someone is going to want to see more data no matter how much you put out)


----------



## The red spirit (Jul 15, 2021)

@VSG 
I opened latest fan review:








						CORSAIR iCUE SP120 RGB ELITE Fan Review
					

CORSAIR adds to their ever-growing fan family with the much-requested SP RGB ELITE fans. Previously only sold with RGB variants of their cases, these new fans offer excellent PWM control over a relatively long RPM range for case fans, coupled with low noise, directed-airflow performance, and the...




					www.techpowerup.com
				




And calculated cfm/dBA ratio of all fans at 1500 rpm. I found some interesting differences. The best fan in this metric was Noctua NF-A1225 PWM, with whopping 0.945 cfm/dBA ratio, meanwhile the worst fan in this metric was Silverstone SST-FM121 (and very close to it was Noctua NF-F12 PWM) it had 0.745 cfm/dBA ratio (0.749 for Noctua F12). Surprisingly enough, that 140mm Silverstone, which imo should be disqualified from here due to not being 120mm fan, while managed to get above average cfm/dBA ratio, it failed to beat Noctua, as it reached 0.905 cfm/dBA. 

I personally think that this metric should be in reviews as it gives a very valuable insight in now fans perform, imo it's more important than just cfm or just dBA. I still don't get it how it ended up being graph hell for you, but if you recalculate it for each tested rpms and then post it as separate graphs, I don't see how it will be problematic.


----------



## FireFox (Jul 15, 2021)

The red spirit said:


> I built quite a bit of systems and only once with radiator.


Shame on you


----------



## The red spirit (Jul 15, 2021)

FireFox said:


> Shame on you


I would only consider water cooling again, if it was custom, without pump, without fans and still would cool stuff quite well. Basically, a big car rad with lots of coolant. For other sane, cost conscious and silent builds, absolutely nothing can touch air cooling. Something like Scythe Mugen 5 PCGH is where it's at.


----------



## mtcn77 (Jul 15, 2021)

The red spirit said:


> @VSG
> I opened latest fan review:
> 
> 
> ...


What you are saying is just like quoting this one article where it says Ice Giant is the latest and greatest invention. It is anectodal. We can't do everything by a single benchmark. There are outliers with every reference point like Ice Giant not being able to cool a 3970X to silicon lottery volts.


----------



## freeagent (Jul 15, 2021)

The red spirit said:


> Scythe Mugen 5 PCGH is where it's at


What makes you say that?


----------



## FireFox (Jul 15, 2021)

I am confused about this:




@VSG what rad did you use for the test?


----------



## VSG (Jul 15, 2021)

FireFox said:


> I am confused about this:
> 
> View attachment 208176
> 
> @VSG what rad did you use for the test?


Swiftech MCRP120QP, based on previous tests to determine a radiator that is average for airflow restriction as well. FYI, the testing details are here: https://www.techpowerup.com/review/darkside-gentle-typhoon-1450-black-edition/4.html

As for the CFM/dB charts, I misunderstood what @The red spirit said and I get it now. It does seem like a good idea, let me see what's the best way to implement it in the future.


----------



## The red spirit (Jul 15, 2021)

freeagent said:


> What makes you say that?


800 rpms or less cools anything on the market.


----------



## FireFox (Jul 15, 2021)

VSG said:


> Swiftech MCRP120QP, based on previous tests to determine a radiator that is average for airflow restriction as well. FYI, the testing details are here: https://www.techpowerup.com/review/darkside-gentle-typhoon-1450-black-edition/4.html


I dont know if i am deaf or what but i have 8x Corsair LL120 RGB and when they run at 750 Rpm i don't hear a thing


----------



## mtcn77 (Jul 15, 2021)

VSG said:


> Swiftech MCRP120QP, based on previous tests to determine a radiator that is average for airflow restriction as well. FYI, the testing details are here: https://www.techpowerup.com/review/darkside-gentle-typhoon-1450-black-edition/4.html
> 
> As for the CFM/dB charts, I misunderstood what @The red spirit said and I get it now. It does seem like a good idea, let me see what's the best way to implement it in the future.


He wants dBA matched temperature charts, not rpm matched temperature charts basically.

PS: @VSG do you have, or plan to test any 38mm(nfa12×15 with nfa12×25) tests in the mean time? I find optimaltech is up to something with the two piece deep section fan assembly.


----------



## VSG (Jul 15, 2021)

FireFox said:


> I dont know if i am deaf or what but i have 8x Corsair LL120 RGB and when they run at 750 Rpm i don't hear a thing


You also probably don't hear these fans from 6" away in an anechoic chamber as those measurements are taken for good SNR.



mtcn77 said:


> He wants dBA matched temperature charts, not rpm matched temperature charts basically.
> 
> PS: @VSG do you have, or plan to test any 38mm(nfa12×15 with nfa12×25) tests in the mean time? I find optimaltech is up to something with the two piece deep section fan assembly.


I have no plans to do temperature charts for fan reviews, it just adds more variables and I'd rather focus on testing purely the purpose of the fan in this aspect which is to blow air through the radiator. 

The EK-Meltemi and the Silverstone fan were the only thick fans I ever planned to do, no one really buys 38 mm fans for PC watercooling.


----------



## The red spirit (Jul 15, 2021)

VSG said:


> As for the CFM/dB charts, I misunderstood what @The red spirit said and I get it now. It does seem like a good idea, let me see what's the best way to implement it in the future.


I had some time to kill and I used that same Corsair fan review to pull data from and I made this Excel file with graph:








						TPU Fans.xlsx
					

Shared with Dropbox




					www.dropbox.com
				




Most fans are pretty much the same, but some stand out. Higher diameter Silverstone fan stood out by offering a lot more airflow at lower rpms for lower noise level, but at high rpms was overtaken by Noctua NF-A12x25. Phanteks PH-F120MP while close to other fans, it was second best after Noctua. All fans seemingly become more efficient at higher rpms, which is something nice to know. Noctua NF-F12 PWM was the worst of the bunch. And for some reason RGB fans seemingly perform worse than their non RGB models. I thought that it had no impact on performance, due to most fans just making transparent ring around blades, but if blades themselves light up, then it's reasonable to expect lower performance by small margin (it probably doesn't matter, but I expected no difference).



VSG said:


> I have no plans to do temperature charts for fan reviews, it just adds more variables and I'd rather focus on testing purely the purpose of the fan in this aspect which is to blow air through the radiator.


That's a good idea, because temperature changes air density and viscosity and you get some rather unpleasant variables to deal with.


----------



## mtcn77 (Jul 15, 2021)

VSG said:


> The EK-Meltemi and the Silverstone fan were the only thick fans I ever planned to do, no one really buys 38 mm fans for PC watercooling.


I mean, not really, just connecting them in the same axial frame. One 15mm fan, one 25mm...
Like this;





I think they haven't tested two different section fans in the same socket, just did a regular push pull setup.


----------



## VSG (Jul 15, 2021)

mtcn77 said:


> I mean, not really, just connecting them in the same axial frame. One 15mm fan, one 25mm...
> 
> 
> Spoiler
> ...


Seems quite impractical aside from a one-off "What happens" style article. But between keyboards, audio, networking, and everything watercooling, there's no time at the present moment sadly.


----------



## freeagent (Jul 15, 2021)

The red spirit said:


> 800 rpms or less cools anything on the market.


I don’t know what you mean by that?


----------



## FireFox (Jul 15, 2021)

freeagent said:


> I don’t know what you mean by that?


That the Scythe Mugen 5 PCGH at 800rpm or less cool anything on the market?

Maybe i am wrong, just guessing


----------



## The red spirit (Jul 15, 2021)

freeagent said:


> I don’t know what you mean by that?


That's the maximum rpms of that thing and it's good enough to cool anything that you can buy.


----------



## freeagent (Jul 15, 2021)

The red spirit said:


> That's the maximum rpms of that thing and it's good enough to cool anything that you can buy.


I don't know.. looks very mid range to me. I wouldn't put it on my 5900. My 5600 maybe if I didn't have another cooler. My 3 main ones right now pretty much destroy it. Looks like it does ok with a quad core.


----------



## mtcn77 (Jul 15, 2021)

freeagent said:


> I don't know.. looks very mid range to me. I wouldn't put it on my 5900. My 5600 maybe if I didn't have another cooler. My 3 main ones right now pretty much destroy it. Looks like it does ok with a quad core.


Mugen 5 is good, but mainstream compared to Fuma 2 which pretty mainstream too(noisewise).


----------



## 80251 (Jul 15, 2021)

The red spirit said:


> Oh well... That's disappointing for sure, but from all data they seem to be good and sometimes chart topping fans. I have bought some other Arctic stuff and its quite solid, fan being out of balance seems like manufacturing defect. I hope that you can RMA them.
> 
> 
> Out of curiosity, what can happen to bearing if it is spun too fast?


It burns up/degrades the lubricant, leading to even more friction. All bearings have races and once the lubricant is gone the race could be scored.



formula383 said:


> Thats not at all the same thing. Engines use fluid bearings, no balls in them. the valve train is what takes a shit first, and then possibly the pistions will seize as the oil gets too hot and gets burned off the cylinder walls.


Not all engines use fluid bearings for the crankshaft. Smaller 4-stroke engines still use roller bearings for the crankshafts.


----------



## The red spirit (Jul 15, 2021)

freeagent said:


> I don't know.. looks very mid range to me. I wouldn't put it on my 5900. My 5600 maybe if I didn't have another cooler. My 3 main ones right now pretty much destroy it. Looks like it does ok with a quad core.


Well, I have Mugen 4 PCGH. It is an excellent cooler. It does cool FX 6300 passively in not so well ventilated case. with fans it can take it to 5GHz+. It wouldn't have any problems with i9 11900K. Mugens generally aren't chart toppers, but they certainly high end performers. They certainly are chart toppers in noise benchmarks. Considering that I got mine for 55 Euros, it's certainly a good value cooler. It was literally more than thrice cheaper than NH-D15 and it was within 2% of performance difference. Not sure how much TweakTown is to be trusted, but they reviewed normal Mugen 5 and it certainly performed very well:





						Scythe Mugen 5 Rev.B CPU Cooler Review
					

Scythe's Mugen 5 Rev.B is one of the best CPU air coolers we have reviewed in recent times. Why? Come and find out.




					www.tweaktown.com
				




You are really underestimating these coolers. I'm quite surprised that TPU never reviewed any Mugen version.


----------



## freeagent (Jul 15, 2021)

Looks pretty decent. Nice to see my Le Grand Macho RT in there kickin up dust. I would still be using it, but FC140 handles my Ryzens better.


----------



## The red spirit (Jul 15, 2021)

freeagent said:


> Looks pretty decent. Nice to see my Le Grand Macho RT in there kickin up dust. I would still be using it, but FC140 handles my Ryzens better.


Imo Ryzen is a trainwreck in terms of heat dissipation. It's very internally bottlenecked by its layout. You know Ryzen is bad at transferring heat to cooler, when you realize that 5950X has a power consumption of Athlon 760K and yet runs a lot hotter. My old FX 6300 technically should run a lot hotter than 5950X, but oh well, it certainly doesn't.


----------



## freeagent (Jul 15, 2021)

Oh yeah I know this. While you were running FX I was giving Mother Nature the finger with my highly clocked x5690.


----------



## looniam (Jul 15, 2021)

The red spirit said:


> Could you link me an example of that?


in case you're still looking.



			Thermalbench.com
		


cheers.


----------



## The red spirit (Jul 15, 2021)

freeagent said:


> Oh yeah I know this. While you were running FX I was giving Mother Nature the finger with my highly clocked x5690.


I don't think I was doing any favours for mother nature by using FX either. I once cranked it to 5.288GHz.


----------



## Falkentyne (Jul 16, 2021)

freeagent said:


> Dude I have iPPC 3000s on my CPU, it is far from silent unless you are completely deaf. I have my PC in the basement, if I turn my fans up all the way I can hear it upstairs on the other side of the house. Most consumer fans are weak to me lol..



Three IPC 3000 120mm and three IPC 3000 140mm Noctua fans, 3x rad and 3x case fans, all running at full 3000 RPM speed.  And I love it.


----------



## freeagent (Jul 16, 2021)

Falkentyne said:


> Three IPC 3000 120mm and three IPC 3000 140mm Noctua fans, 3x rad and 3x case fans, all running at full 3000 RPM speed.  And I love it.


I did wonder what a case full of them sounded like.. might have to take you up on that lol 

Edit: 

Amazon.ca is out of 140s.. I may sneak in a couple of 140  2K temporarily and I can use them on my other pc when 140 3K comes back in stock.


----------



## Falkentyne (Jul 17, 2021)

freeagent said:


> I did wonder what a case full of them sounded like.. might have to take you up on that lol
> 
> Edit:
> 
> Amazon.ca is out of 140s.. I may sneak in a couple of 140  2K temporarily and I can use them on my other pc when 140 3K comes back in stock.



Can't buy these?





						Amazon.com: Noctua NF-A14 iPPC-3000 PWM, Heavy Duty Cooling Fan, 4-Pin, 3000 RPM (140mm, Black) : Electronics
					

Buy Noctua NF-A14 iPPC-3000 PWM, Heavy Duty Cooling Fan, 4-Pin, 3000 RPM (140mm, Black): Case Fans - Amazon.com ✓ FREE DELIVERY possible on eligible purchases



					www.amazon.com


----------



## freeagent (Jul 17, 2021)

Falkentyne said:


> Can't buy these?
> 
> 
> 
> ...


I can get them from the states, but they were on sale and now there is a seller on there that has them listed for double price. I could line the case in 120s.. the price of those fans has me considering a new mobo and hand mine off to the kids machine.


----------



## formula383 (Jul 17, 2021)

The red spirit said:


> Imo Ryzen is a trainwreck in terms of heat dissipation. It's very internally bottlenecked by its layout. You know Ryzen is bad at transferring heat to cooler, when you realize that 5950X has a power consumption of Athlon 760K and yet runs a lot hotter. My old FX 6300 technically should run a lot hotter than 5950X, but oh well, it certainly doesn't.


apples to oranges mate. the thermal sensors are not reading the same points. FX series actually idles below ambitent temps meaning its being offset for quiet fan profiles or who knows why. The TJM was what 75deg on FX? As for older CPU's most of them were reading cpu socket temps hence why the old 60deg C was considered max temps. So every cpu evermade has been a thermal trainwreck when you push them to the limits. hence why back in the day they limited clocks so much, they knew more clocks wont really net that much more performance at the cost of much higher power draw and temps leading to more warranty cpu's because people never watch cpu temps. But its a bit of a differnt world now. so many years of OCers talking about how they want clock speed actually changed the market. Reviewers are looking at game performance like never before. all this helped to change the state of current cpu's and how they are marketed. (for better or worse)


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## Shrek (Jul 17, 2021)

Falkentyne said:


> Three IPC 3000 120mm and three IPC 3000 140mm Noctua fans, 3x rad and 3x case fans, all running at full 3000 RPM speed.  And I love it.



Not a bit noisy?


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## freeagent (Jul 17, 2021)

Andy Shiekh said:


> Not a bit noisy?


I only have two and they are pretty loud when they spool up. Of course you can set limits but that’s no fun..


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## The red spirit (Jul 18, 2021)

formula383 said:


> apples to oranges mate. the thermal sensors are not reading the same points. FX series actually idles below ambitent temps meaning its being offset for quiet fan profiles or who knows why. The TJM was what 75deg on FX?


It was 62C, later changed to 72.4C. 



formula383 said:


> As for older CPU's most of them were reading cpu socket temps hence why the old 60deg C was considered max temps


FX had CPU sensor, but it had temperature offset for some reason.



formula383 said:


> So every cpu evermade has been a thermal trainwreck when you push them to the limits.


No, just no.



formula383 said:


> hence why back in the day they limited clocks so much, they knew more clocks wont really net that much more performance at the cost of much higher power draw and temps leading to more warranty cpu's because people never watch cpu temps.


Duh, that's like exactly like today and nope they pushed clock speed a lot. FX 6300 Turbo was 4.1GHz. FX 6350 turbo was 4.3GHz. FX 9590 had base 4.7GHz and Turbo of 5GHz. 9370 had base of 4.4GHz and Turbo of 4.7GHz. i7 4790K had turbo of 4.4GHz. That's just a bit less than today. 




formula383 said:


> But its a bit of a differnt world now. so many years of OCers talking about how they want clock speed actually changed the market.


Not really all that much.



formula383 said:


> Reviewers are looking at game performance like never before.


Just like they always did. If they didn't, we would still be fine with 3dfx VooDoos.


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