Airflow vs static pressure fans. Are they a scam?

[formula383]

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]

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

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).

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]

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.

 

[cvaldes]

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]

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]

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]

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]

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]

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]

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

 

[Ominence]

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]

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.

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]

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

 

[The red spirit]

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]

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

 

[The red spirit]

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]

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

 

[mtcn77]

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.

 

[The red spirit]

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).

 

[mtcn77]

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.

 

[freeagent]

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..

 

[The red spirit]

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.

 

[mtcn77]

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.

 

[formula383]

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]

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.

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