If top blowing coolers are so good, why they are so uncommon?

[docnorth]

Yeah, but not volumetrically 9 times as efficient as air bearing coolers. Cooling is about removing the stagnant layer over the fin array. You can't do that with positive pressure alone.

Well this is another BIGGER discussion about airflow...

 

[mtcn77]

Well this is another BIGGER discussion about airflow...

Yes negative versus positive pressure cooling principles and harnessing the atmospheric pressure to your benefit. All good coolers want to create turbulence, but it should be obvious just sweeping the air across over an object can provide ventilation on it according to Bernoulli's Principle. Hence, tower coolers are predominant.

 

[Blue4130]

. Cooling is about removing the stagnant layer over the fin array. You can't do that with positive pressure alone.

This is a rediculous statement. Of course you can cool (remove) stagnant air with positive pressure alone.

 

[mtcn77]

This is a rediculous statement. Of course you can cool (remove) stagnant air with positive pressure alone.

To an extent... if you use negative pressure by sucking air out, it stops lying still and you can use the whole fin.

Perhaps, I stated it wrong: spinning the fin causes inertia to move air away from the fin. It is not about pressure, as much as inertia.

 

[Blue4130]

To an extent... if you use negative pressure by sucking air out, it stops lying still and you can use the whole fin.

Perhaps, I stated it wrong: spinning the fin causes inertia to move air away from the fin. It is not about pressure, as much as inertia.

It does the exact same thing with positive pressure.

 

[mtcn77]

It does the exact same thing with positive pressure.

But the flow does not carry the same velocity over the fin. Hence the coined isolating air term comes from,

In a conventional CPU cooler, the heat transfer bottleneck is the boundary layer of “dead air.

It also works according to the principle of turbulence to exchange heat, not laminar flow.

 

[mama]

Yeah, but not volumetrically 9 times as efficient as air bearing coolers. Cooling is about removing the stagnant layer over the fin array. You can't do that with positive pressure alone.

Apparently you can:

Noctua NH-P1 Fanless CPU Cooler Released for $100​

by btarunr Jun 7th, 2021 12:45 Discuss (37 Comments)
Noctua's ambitious 100% fanless CPU heatsink, the NH-P1, was briefly listed on Newegg for $100. The heatsink offers clearance for standard-height memory and VRM heatsinks of most motherboards; and completely fanless cooling due to the sheer amount of surface area on offer to dissipate heat without the need for an active airflow. The design of the NH-P1 involves a nickel-plated copper base, from which six heat-pipes emerge passing through a gargantuan aluminium fin-stack.

Noctua claims that the cooler can handle mainstream desktop CPUs without the need for fans. These include the Core i9-9900K, Ryzen 7 2700X, etc., which should mean that most non-K 10th Gen and 11th Gen Intel processors; as well as Ryzen 3000 and Ryzen 5000 chips up to 8 cores should run perfectly fine with this heatsink. Among the CPU socket types supported are LGA1200, LGA115x, LGA2066, and AM4. For higher TDP chips, particularly HEDT chips in the LGA2066 package, the heatsink supports the mounting of a pair of 120 mm fans.

 

[claes]

I think Mtcn77 is talking about air bearing coolers, like Sandia was developing a decade ago

 

[maxfly]

Has there ever been a high end top down cooler that out performed high end tower coolers? They've always been inferior. Other than being able to fit in tight spaces of course.

 

[mtcn77]

I think Mtcn77 is talking about air bearing coolers, like Sandia was developing a decade ago

I checked back on them and the claims are more exaggerated than I remembered - 30 times more compact, instead of 9!

 

[eidairaman1]

I have read a lot about how top blowing coolers are good and with certain boards mandatory. They seemingly help to cool VRMs and at the same time they are usually as good as single tower 120mm coolers. And despite seemingly being great particularly for budget overclockers, they are really uncommon. So far, today only competent downdraft coolers are Scythe Choten, Noctua NH-C14 and BQ Shadow Rock TF2. If they are good and help to cool down motherboard (VRM heat is still a big problem), why they are still so uncommon? It's not like they are new or anything, Scythe made Andy Samurai Master in 2003, so they are very well known and likely one of the first big upgrade over stock Athlon XP or Pentium 4 (socket 423) heatsink. I'm pretty sure that they can be manufactured rather well and they aren't really more expensive than single tower 120mm heatsinks.

Space constraints.

 

[mtcn77]

Space constraints.

Also, laminar air sound volume is a wild card in comparison to turbulent air exchange principles.

Has there ever been a high end top down cooler that out performed high end tower coolers? They've always been inferior. Other than being able to fit in tight spaces of course.

They didn't develop the technology blaming machinery tolerances. Someone copied the design and quickly handed off to thermaltake after receiving a medal. Quite pathetic how its mimic overshadowed it really. The original had variable blade thickness design.

 

[The red spirit]

Apparently you can:

Noctua NH-P1 Fanless CPU Cooler Released for $100​

by btarunr Jun 7th, 2021 12:45 Discuss (37 Comments)
Noctua's ambitious 100% fanless CPU heatsink, the NH-P1, was briefly listed on Newegg for $100. The heatsink offers clearance for standard-height memory and VRM heatsinks of most motherboards; and completely fanless cooling due to the sheer amount of surface area on offer to dissipate heat without the need for an active airflow. The design of the NH-P1 involves a nickel-plated copper base, from which six heat-pipes emerge passing through a gargantuan aluminium fin-stack.

Noctua claims that the cooler can handle mainstream desktop CPUs without the need for fans. These include the Core i9-9900K, Ryzen 7 2700X, etc., which should mean that most non-K 10th Gen and 11th Gen Intel processors; as well as Ryzen 3000 and Ryzen 5000 chips up to 8 cores should run perfectly fine with this heatsink. Among the CPU socket types supported are LGA1200, LGA115x, LGA2066, and AM4. For higher TDP chips, particularly HEDT chips in the LGA2066 package, the heatsink supports the mounting of a pair of 120 mm fans.

It's natural convection + gravity, so air isn't exactly stagnant.

Space constraints.

Downdraft coolers are often less taller. My Choten is just 120mm tall, so it does fit in many more places than just 120mm tower cooler which would be 140-150mm tall. Downdraft cooler does need some gap left to breathe, but still, it's as convenient as basic tower.

 

[Space Lynx]

I get around this the VRM heat problem by just buying a beefy mobo, that in reviews always rates great VRM temps, then even with no airflow, I still have peace of mind. Don't cheap out on your mobo is the name of the game imo.

 

[The red spirit]

I get around this the VRM heat problem by just buying a beefy mobo, that in reviews always rates great VRM temps, then even with no airflow, I still have peace of mind. Don't cheap out on your mobo is the name of the game imo.

If you overclock, your VRM gets hotter too. No way around that. And some not so cheap boards are also nowadays burning piles of VRM too, so even if you spend more, you may get poo poo. Pretty much budget overclocking is dead.

 

[eidairaman1]

It's natural convection + gravity, so air isn't exactly stagnant.


Downdraft coolers are often less taller. My Choten is just 120mm tall, so it does fit in many more places than just 120mm tower cooler which would be 140-150mm tall. Downdraft cooler does need some gap left to breathe, but still, it's as convenient as basic tower.

Ok certain top down coolers would hit the side of the case and restrict air flow.

Scythe had a huge 1 long ago

 

[Blue4130]

But the flow does not carry the same velocity over the fin. Hence the coined isolating air term comes from,

It also works according to the principle of turbulence to exchange heat, not laminar flow.

Why does it not carry the same velocity? The bernoulli principle is highly suspect due to coolers not being sealed at all and the fan restricting any increase in velocity related. I highly, highly doubt that there is enough of a pressure differential to cause increased flow.

 

[The red spirit]

Ok certain top down coolers would hit the side of the case and restrict air flow.

Scythe had a huge 1 long ago

lol Scythe Godhand? That thing is quite extreme I must say:

I'm not even sure if they released it, I only see photos of demonstration. And they certainly made Scythe Susanoo:

Now that's some legit "holy shit" stuff. It has 4 100mm fans. Why make it fit into case, when you can make it so big that cooler itself becomes your new side panel. Those people at Scythe are insane and I love them.

 

[Space Lynx]

If you overclock, your VRM gets hotter too. No way around that. And some not so cheap boards are also nowadays burning piles of VRM too, so even if you spend more, you may get poo poo. Pretty much budget overclocking is dead.

that's why you read vrm hot spot reviews before you buy any mobo. i bought my x570 tomahawk early last year and that sucker didn't even break a sweat.

 

[mtcn77]

Why does it not carry the same velocity? The bernoulli principle is highly suspect due to coolers not being sealed at all and the fan restricting any increase in velocity related. I highly, highly doubt that there is enough of a pressure differential to cause increased flow.

Because air doesn't move when there is no pressure difference(forced air doesn't travel equally, bernoulli principle dictates faster zones are travelled more frequently). We may force convection, but there is a boundary layer. Only solution is making a spinning fin array if we want to use 100% of surface area.It is quite elegant to do so, don't mistake it with the thermaltake contraption which have vanes! Think about their air restriction.

 

[The red spirit]

that's why you read vrm hot spot reviews before you buy any mobo. i bought my x570 tomahawk early last year and that sucker didn't even break a sweat.

Words of caution: HWUB tests boards in open air at about 24C. Not realistic scenario at all.

 

[mtcn77]

Words of caution: HWUB tests boards in open air at about 24C. Not realistic scenario at all.

Also Linus and all the others...

 

[Blue4130]

Because air doesn't move when there is no pressure difference(forced air doesn't travel equally, bernoulli principle dictates faster zones are travelled more frequently). We may force convection, but there is a boundary layer. Only solution is making a spinning fin array if we want to use 100% of surface area.It is quite elegant to do so, don't mistake it with the thermaltake contraption which have vanes! Think about their air restriction.

But positive pressure is a pressure differential just as negative. Why do you think one is better than the other?

 

[mtcn77]

But positive pressure is a pressure differential just as negative. Why do you think one is better than the other?

Because of Bernoulli principle. Air isn't water, you cannot make it move at the same velocity unless you can eradicate friction on the fins(self defeating predicament, friction causes heat exchange). When the middle layer accelerates, heat exchange at the fin boundary creates a virtual vacuum as air doesn't travel there. What little stays creates an air pocket. Positive pressure while working uses energy and makes noise in return. Not the exact results you want.

 

[The red spirit]

I just now realized that Noctua didn't really make that passive cooler, they just copied Scythe and their Orochi cooler:

Reputation lost, Noctua is still a wanker company.