[SOLVED] Why don't companies make graphics cards with very large centrifugal fans (and why not 2 or 3)?

guymarshall

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I understand that axial fans can keep a card cooler and quieter whilst achieving higher clock speeds, but the axial fans used on cards like strix and windforce cards are massive in terms of width and height, and there are always 2 or 3 instead of just 1 so it isn't really fair.

I am wondering why companies don't make a massive thick heatsink graphics card like the ROG Strix 2080 ti and instead of 3 axial fans, put one massive (or 2/3 massive) centrifugal fans on it to offer the advantage that centrifugal fans have of much higher static pressure. The noise of larger fans is generally less because they run at a lower RPM, the heat will be exhausted out the case, it seems like a win-win situation!

Is there something I am overlooking? I would love to see a card like the Strix 970 have 2 centrifugal fans on it as it would look pretty awesome and wouldn't cook the insides of many small cases with poor airflow.

View: https://imgur.com/a/58PZ133
(the example of a thick heatsink on the axial card vs a thin heatsink on the centrifugal card)
 
No worries. Yeah, even I actually prefer blower-type cooler GPUs, LOL.

I have had pretty compact and Mini-ITX cabinets in the past, so a blower Model helped to flush out the hot air from the rear. I've used an R9 290 GPU before, Though, it was running quite hot !

I think this all depends on choice, if you prefer a blower style cooling, or a single/dual/triple fan design for the PCB (Open Air) ? But these reference type GPUs can get noisy under load though. It also depends on what type of ATX cabinet you are having.

The blower cooler will help push the hot air from the near of the chassis. It sucks air in through the single fan in the front of the card and blows it out of the back. It is important to note that even though all blower-type coolers use a single-fan design, not all single-fan cards are blower-style.

Exhausting air out the back of the card helps in cases with poor airflow since there is no hot air blown into the case; conversely, it is exhausted outside of the chassis.

On the other hand, the volume of that air is usually so small that the single tiny fan must spin much faster to cool the GPU properly, meaning most blower style cards are susceptible to higher temperatures and noise levels compared to their competition. Blower coolers are generally most useful in mini-ITX cases and/or multi-GPU setups, where there is not enough case airflow available to sustain an open-air cooler design.

The logic behind open-air cards is also simple, a cooler with a single, double, or triple fan that blows cold air from the outside onto a heatsink – either directly or indirectly cooling the GPU. The radiator usually consists of fins that have heatpipes running through them. Blower-style cards use smaller heatsinks, which is one of the reasons why their cooling capacity is much smaller.
 
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guymarshall

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I think there are less buyers for a Blower-type reference cooler GPU model. Many prefer an open air model. Though, this also depends on what type of chassis they are using.

I've never seen a DUAL blower fan model though.
Thanks for the quick reply, I had emails muted -_- sorry about that! Yeah I guess there is a smaller market, but the performance could be significantly higher with just a normal sized (or comparable to the axial fans) centrifugal fans. Imagine a blower of the same size as an axial with better performance, similar noise, and no heat into the case. Its just perfect! :) I also absolutely love the look of blowers tbh haha
 
No worries. Yeah, even I actually prefer blower-type cooler GPUs, LOL.

I have had pretty compact and Mini-ITX cabinets in the past, so a blower Model helped to flush out the hot air from the rear. I've used an R9 290 GPU before, Though, it was running quite hot !

I think this all depends on choice, if you prefer a blower style cooling, or a single/dual/triple fan design for the PCB (Open Air) ? But these reference type GPUs can get noisy under load though. It also depends on what type of ATX cabinet you are having.

The blower cooler will help push the hot air from the near of the chassis. It sucks air in through the single fan in the front of the card and blows it out of the back. It is important to note that even though all blower-type coolers use a single-fan design, not all single-fan cards are blower-style.

Exhausting air out the back of the card helps in cases with poor airflow since there is no hot air blown into the case; conversely, it is exhausted outside of the chassis.

On the other hand, the volume of that air is usually so small that the single tiny fan must spin much faster to cool the GPU properly, meaning most blower style cards are susceptible to higher temperatures and noise levels compared to their competition. Blower coolers are generally most useful in mini-ITX cases and/or multi-GPU setups, where there is not enough case airflow available to sustain an open-air cooler design.

The logic behind open-air cards is also simple, a cooler with a single, double, or triple fan that blows cold air from the outside onto a heatsink – either directly or indirectly cooling the GPU. The radiator usually consists of fins that have heatpipes running through them. Blower-style cards use smaller heatsinks, which is one of the reasons why their cooling capacity is much smaller.
 
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guymarshall

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No worries. Yeah, even I actually prefer blower-type cooler GPUs, LOL.

I have had pretty compact and Mini-ITX cabinets in the past, so a blower Model helped to flush out the hot air from the rear. I've used an R9 290 GPU before, Though, it was running quite hot !

I think this all depends on choice, if you prefer a blower style cooling, or a single/dual/triple fan design for the PCB (Open Air) ? But these reference type GPUs can get noisy under load though. It also depends on what type of ATX cabinet you are having.

The blower cooler will help push the hot air from the near of the chassis. It sucks air in through the single fan in the front of the card and blows it out of the back. It is important to note that even though all blower-type coolers use a single-fan design, not all single-fan cards are blower-style.

Exhausting air out the back of the card helps in cases with poor airflow since there is no hot air blown into the case; conversely, it is exhausted outside of the chassis.

On the other hand, the volume of that air is usually so small that the single tiny fan must spin much faster to cool the GPU properly, meaning most blower style cards are susceptible to higher temperatures and noise levels compared to their competition. Blower coolers are generally most useful in mini-ITX cases and/or multi-GPU setups, where there is not enough case airflow available to sustain an open-air cooler design.

The logic behind open-air cards is also simple, a cooler with a single, double, or triple fan that blows cold air from the outside onto a heatsink – either directly or indirectly cooling the GPU. The radiator usually consists of fins that have heatpipes running through them. Blower-style cards use smaller heatsinks, which is one of the reasons why their cooling capacity is much smaller.
Ouch I remember the 290, 290x and 295x2 days hahaha what a space heater!! Tbh I prefer using them in full size ATX cases and open-air test benches because of the appearance. I also like the efficiency of moving the air the same direction of the fan movement, as oppose to the air hitting the axial motor and kind of being squished around it inefficiently. But damn I wish companies made larger centrifugal fans and massive heatsinks. One argument for this is there is only 1 fan so surely all that extra space can be fins?
 
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guymarshall

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Indeed. Even the R9 300 series was a hot running CHIP. Thankfully AMD has improved a lot on their GCN design in the RX 400/500 series, the VEGA and Rx 5700 series of cards.

But still not power efficient than NVIDIA"s counterparts.
They definitely have and I sometimes love to look back at what AMD used to be in 2012 with their FX-8350 (that I still have to this day) and now look at their monstrous 2990 WX. Intel really needs to up their game, and although they aren't the fastest in graphics by any means, they are climbing quickly with the 5700 XT!
 
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digitalgriffin

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The problem with centrifugal fans is they blow air OUTWARD perpendicular to the axis of rotation, versus Axials which blow it DOWNWARD parallel to the axis of rotation. The problem with this is you get boundary issues. This is where the air is slamming into some sort of wall/barrier. And it's high pressure air at that. This generates a lot of noise. Also the high pressure gradient creates a "Vacuum" towards the middle of the fan at high RPMs as air gets sucked from the middle towards the outside edges. Typically you are starving the fan intake. Cutting the wheel in half and using DWDI helps alleviate some of this, but it isn't a cure all and wouldn't be practical for a middle set design. These pressure gradients cause a lot of noise when they interact with surfaces. These are known as boundary layer interactions.

To add to this, you'll have to redirect that air to flow down the fin path. You could technically place it sunken in the middle of two radiators, but you'll still encounter boundary issues at the top of bottom.

Signed,
An aerospace engineer who also has a degree in computer science working in a related industry.

I could design a really @#$@#%$#@ setup that was both cool and quiet. But it wouldn't be practical to most.
 
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guymarshall

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The problem with centrifugal fans is they blow air OUTWARD perpendicular to the axis of rotation, versus Axials which blow it DOWNWARD parallel to the axis of rotation. The problem with this is you get boundary issues. This is where the air is slamming into some sort of wall/barrier. And it's high pressure air at that. This generates a lot of noise. Also the high pressure gradient creates a "Vacuum" towards the middle of the fan at high RPMs as air gets sucked from the middle towards the outside edges. Typically you are starving the fan intake. Cutting the wheel in half and using DWDI helps alleviate some of this, but it isn't a cure all and wouldn't be practical for a middle set design. These pressure gradients cause a lot of noise when they interact with surfaces. These are known as boundary layer interactions.

To add to this, you'll have to redirect that air to flow down the fin path. You could technically place it sunken in the middle of two radiators, but you'll still encounter boundary issues at the top of bottom.

Signed,
An aerospace engineer who also has a degree in computer science working in a related industry.
Wow that's a lot of information thank you very much!! I was under the same theory that bigger slower axial fans are better, and push-pull increases performance, so it must do the same for centrifugal fans! :)
 

digitalgriffin

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Wow that's a lot of information thank you very much!! I was under the same theory that bigger slower axial fans are better, and push-pull increases performance, so it must do the same for centrifugal fans! :)
You could technically set it up so that the Centrifugal fan PULLS* air from outside edges inward , and then exhaust the hot air into the case. That would be less noise provided there was no shroud around the moving blades. It would be interesting setup for sure. This would be akin to your vacuum cleaner motor sucking air from the intake and blowing it out into the room.

*(Technically speaking higher case atmosphere pressure would PUSH air into the radiator fins toward the fan where the pressure is lower.)
 
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guymarshall

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You could technically set it up so that the Centrifugal fan PULLS* air from outside edges inward , and then exhaust the hot air into the case. That would be less noise provided there was no shroud around the moving blades. It would be interesting setup for sure. This would be akin to your vacuum cleaner motor sucking air from the intake and blowing it out into the room.

*(Technically speaking higher case atmosphere pressure would PUSH air into the radiator fins toward the fan where the pressure is lower.)
Ohh so like a reverse axial almost! And yeah that makes sense for the air to move to lower pressure zones, and tbh I quite like the noise as it indicates performance :p
 

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