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

[Guy Marshall]

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. Is multiple centrifugal fans blowing in the same direction (like push pull) even possible?

 

https://imgur.com/a/58PZ13/ (the example of large axial fans vs a single smaller centrifugal fan)

 

 

- I am a massive fan of centrifugal fans, and I think they are far better than people think but they are also made too small for these applications in my opinion

[Zando_]

For a bigger centrifugal fan wouldn't you need to cut out more of the heatsink (due to the fact they need to be sunk in to work properly, whereas axials can just sit on top), forcing you to run it at a higher RPM to compensate? 

[Guy Marshall]

2 minutes ago, Zando Bob said:

For a bigger centrifugal fan wouldn't you need to cut out more of the heatsink (due to the fact they need to be sunk in to work properly, whereas axials can just sit on top), forcing you to run it at a higher RPM to compensate? 

Thanks for the quick reply! You make a great point that I never even thought about! I suppose you could stick the fan to the very far side of the card as much as possible and fill the rest of the card in as many fins as possible? Or make the card much longer as some high end cards already do. Not sure if this is feasible or not though!

[Zando_]

Just now, Guy Marshall said:

Thanks for the quick reply! You make a great point that I never even thought about! I suppose you could stick the fan to the very far side of the card as much as possible and fill the rest of the card in as many fins as possible? Or make the card much longer as some high end cards already do. Not sure if this is feasible or not though!

It should be, see the Vega FE cooler: 

 

If they made it a bit wider like AIB cards (see the EVGA FTW series and MSI Gaming and such, they make the actual PCB and card wider and a little bit longer) they could fit a bigger fan, and then there's a good amount of space to fit a larger heatsink. Making the GPU slightly thicker (2 1/4 slot or something) could let you get in a thicker set of fins. Would be interesting to see how a blower cooler given the AIB treatment would perform. 

Similar thing on the Radeon VII, they cut out the heatsink to fit in axial fans but stay in a strict 2 slot form factor, and didn't make the card any wider either so it lost a lot of fin density, thus why it performs pretty badly. AIBs typically don't make derped mistakes like that on their higher end coolers, thus why it'd be interesting to see a blower pushed to the absolute max. 

[Mira Yurizaki]

The main problem with centrifugal fans is space. They take up a lot of volume for the amount of air they can push. You also can't really make the card longer because 12" is already pushing it.

 

If anything, I wish they would design the heat sink so the fins run front to back rather than side to side. If it's front to back, at least some of the air will be pushed out through the back of the case. And while people might go "but muh vortexes because the front side clashes with the intakes of the case." I imagine as long as the volume of air below the fans isn't significantly disturbed, the fans are going to push up the same volume of air regardless of airflow issues elsewhere.

[Guy Marshall]

1 minute ago, Zando Bob said:

It should be, see the Vega FE cooler: 

 

If they made it a bit wider like AIB cards (see the EVGA FTW series and MSI Gaming and such, they make the actual PCB and card wider and a little bit longer) they could fit a bigger fan, and then there's a good amount of space to fit a larger heatsink. Making the GPU slightly thicker (2 1/4 slot or something) could let you get in a thicker set of fins. Would be interesting to see how a blower cooler given the AIB treatment would perform. 

Similar thing on the Radeon VII, they cut out the heatsink to fit in axial fans but stay in a strict 2 slot form factor, and didn't make the card any wider either so it lost a lot of fin density, thus why it performs pretty badly. AIBs typically don't make derped mistakes like that on their higher end coolers, thus why it'd be interesting to see a blower pushed to the absolute max. 

Ahh I have never seen that card taken apart before! But what astounds me is why is the heatsink so small? Surely the fan can have heatsink on either side (the air will travel in that general direction to pull from one and push to the other) and the entire of the card should be heatsink? Very strange!

[Guy Marshall]

1 minute ago, Mira Yurizaki said:

The main problem with centrifugal fans is space. They take up a lot of volume for the amount of air they can push. You also can't really make the card longer because 12" is already pushing it.

 

If anything, I wish they would design the heat sink so the fins run front to back rather than side to side. If it's front to back, at least some of the air will be pushed out through the back of the case. And while people might go "but muh vortexes because the front side clashes with the intakes of the case." I imagine as long as the volume of air below the fans isn't significantly disturbed, the fans are going to push up the same volume of air regardless of airflow issues elsewhere.

True that can easily be missed! I am wondering if you can put 2/3 centrifugal fans in push-pull and put heatsinks between the fans and in front of them for maximum performance. This would mean each individual fan spins more slowly and the airflow is increased? I might be missing something though!

[Zando_]

6 minutes ago, Guy Marshall said:

Ahh I have never seen that card taken apart before! But what astounds me is why is the heatsink so small? Surely the fan can have heatsink on either side (the air will travel in that general direction to pull from one and push to the other) and the entire of the card should be heatsink? Very strange!

Yeah, when I took mine apart I was surprised by how teeny tiny the finstack is. The fan setup is logical though, due to how that fan works. It sucks air in the center opening on the aluminum shroud (if you've ever built a water pump with a motor, hot glue stick, and film canister, this does the same thing), then pushes it out the edges. They have the kind of snail looking walls around it to spin the air around and push all of it out the back of the card. It does this very, very, very well indeed. If you ramp up the fans the airflow out the back of the card is insane, it pushes pretty much all the hot air it makes out of the case. 

The heatsink could use a rework to be bigger (thus why I'd make the card wider, longer, and a bit thicker), and then make the fan a bit bigger too. 

 

4 minutes ago, Guy Marshall said:

True that can easily be missed! I am wondering if you can put 2/3 centrifugal fans in push-pull and put heatsinks between the fans and in front of them for maximum performance. This would mean each individual fan spins more slowly and the airflow is increased? I might be missing something though!

Due to how they work I don't think they'd behave very well in push/pull. Like I just explained above, the single, small fan on the Vega FE has some insane static pressure, pushing air through a damn thicc finstack wouldn't be any issue. In push/pull you'd have to stack them on top of each other, they inhale air in the top and push it out the sides, vs axial fans that push it out the bottom. If you put them next to each other like axial fans, they'd push air in the sides of the others and bork the airflow. 

[DildorTheDecent]

 

1 minute ago, Zando Bob said:

thus why it'd be interesting to see a blower pushed to the absolute max. 

I unlocked the fan speed on my GTX 660 from 70% to 100% a while ago.

 

The sound was insane. Power usage was nuts too. Pushing into the realm of 20Ws. Way too much for a GPU fan given the limited power budget.

 

Temps were great though.

[Guy Marshall]

Just now, DildorTheDecent said:

 

I unlocked the fan speed on my GTX 660 from 70% to 100% a while ago.

 

The sound was insane. Power usage was nuts too. Pushing into the realm of 20Ws. Way too much for a GPU fan given the limited power budget.

 

Temps were great though.

20W that's crazy!! I have seen overclocks at their limit and when the fan speed increases it lowers clock speed, but 20W is absolutely crazy!

[Guy Marshall]

1 minute ago, Zando Bob said:

Yeah, when I took mine apart I was surprised by how teeny tiny the finstack is. The fan setup is logical though, due to how that fan works. It sucks air in the center opening on the aluminum shroud (if you've ever built a water pump with a motor, hot glue stick, and film canister, this does the same thing), then pushes it out the edges. They have the kind of snail looking walls around it to spin the air around and push all of it out the back of the card. It does this very, very, very well indeed. If you ramp up the fans the airflow out the back of the card is insane, it pushes pretty much all the hot air it makes out of the case. 

The heatsink could use a rework to be bigger (thus why I'd make the card wider, longer, and a bit thicker), and then make the fan a bit bigger too. 

 

Due to how they work I don't think they'd behave very well in push/pull. Like I just explained above, the single, small fan on the Vega FE has some insane static pressure, pushing air through a damn thicc finstack wouldn't be any issue. In push/pull you'd have to stack them on top of each other, they inhale air in the top and push it out the sides, vs axial fans that push it out the bottom. If you put them next to each other like axial fans, they'd push air in the sides of the others and bork the airflow. 

Ah yeah airflow will indeed be borked my bad! But when you said the card could be bigger, I have a Strix 970 and although it could be longer it is very tall, and if it had a blower fan that size I cannot imagine the performance! I love how coolers have come to the point that they can happily keep an overclocked 2080 ti under TjMax even with some blowers! A few years ago with the older blowers that's unheard of!

[Zando_]

1 minute ago, Guy Marshall said:

Ah yeah airflow will indeed be borked my bad! But when you said the card could be bigger, I have a Strix 970 and although it could be longer it is very tall, and if it had a blower fan that size I cannot imagine the performance! I love how coolers have come to the point that they can happily keep an overclocked 2080 ti under TjMax even with some blowers! A few years ago with the older blowers that's unheard of!

Exactly, only issue they really have is noise. The Vega FE is a hot card, but the stock cooler could easily keep it under 70-75C, just it sounds like a jet engine and could be used as an effective leafblower if your PC was portable (again, insane static pressure). 

 

I wonder if there's a reason for centrifugal fans being smaller though, do they not scale well? Do you get better static pressure from a big but slower moving fan, or a small, very fast spinning fan? I don't know the physics behind it but I think due to how they work they do need to spin pretty fast. 

[Guy Marshall]

Just now, Zando Bob said:

Exactly, only issue they really have is noise. The Vega FE is a hot card, but the stock cooler could easily keep it under 70-75C, just it sounds like a jet engine and could be used as an effective leafblower if your PC was portable (again, insane static pressure). 

 

I wonder if there's a reason for centrifugal fans being smaller though, do they not scale well? Do you get better static pressure from a big but slower moving fan, or a small, very fast spinning fan? I don't know the physics behind it but I think due to how they work they do need to spin pretty fast. 

Well all the air compressors use centrifugal fans so I assume they are better but then graphics cards don't? Maybe too much force on the caps on the boards. And I'm not sure but maybe sound will be lowered with a slower bigger fan over a faster smaller one

[Zando_]

Just now, Guy Marshall said:

Well all the air compressors use centrifugal fans so I assume they are better but then graphics cards don't? Maybe too much force on the caps on the boards. And I'm not sure but maybe sound will be lowered with a slower bigger fan over a faster smaller one

Aha: 

 

Running them in a series will increase the static pressure if you have the snail housings to push the air into the other fans properly. I don't think that's what you need on a GPU though, they already have insane static pressure. Buuuuttt.. if you stack them in a parallel they push more air with a lower static pressure. I wonder if stacking two slimmer centrifugal fans would reduce noise but still push plenty of air with a decent static pressure? My 2012 MacBook pro uses a very small centrifugal fan: 

 

At 2-3 thousand RPM I can't hear it (it's at 2002rpm right now and is inaudible). It doesn't push a ton of air, but that's because it's so tiny. I wonder if you used a similar design, but 90-100mm, if that'd cut down noise and then you could stack two instead of a single, louder fan and still push air cleanly out of the chassis. 

[Guy Marshall]

3 minutes ago, Zando Bob said:

Aha: 

 

Running them in a series will increase the static pressure if you have the snail housings to push the air into the other fans properly. I don't think that's what you need on a GPU though, they already have insane static pressure. Buuuuttt.. if you stack them in a parallel they push more air with a lower static pressure. I wonder if stacking two slimmer centrifugal fans would reduce noise but still push plenty of air with a decent static pressure? My 2012 MacBook pro uses a very small centrifugal fan: 

 

At 2-3 thousand RPM I can't hear it (it's at 2002rpm right now and is inaudible). It doesn't push a ton of air, but that's because it's so tiny. I wonder if you used a similar design, but 90-100mm, if that'd cut down noise and then you could stack two instead of a single, louder fan and still push air cleanly out of the chassis. 

Very interesting link! I tried looking and couldn't find anything lol so thanks! I guess Apple makes the fans spin more slowly to have less noise, but if you triple the fan size, at the same speed it will easily cool a graphics card whilst being incredibly quiet. Also the other way I guess a super small fan that spins at 8000 rpm to move the same air will cool the card the same but sound horrendous! Physics is so amazing!

[Zando_]

2 minutes ago, Guy Marshall said:

Very interesting link! I tried looking and couldn't find anything lol so thanks! I guess Apple makes the fans spin more slowly to have less noise, but if you triple the fan size, at the same speed it will easily cool a graphics card whilst being incredibly quiet. Also the other way I guess a super small fan that spins at 8000 rpm to move the same air will cool the card the same but sound horrendous! Physics is so amazing!

Now I lowkey want to get my hands on some old cheap blower cards and chop them up then jank together the finstacks and find different sized fans to see if there's a difference. Also I wonder if as much work has gone into optimizing centrifugal fans as axials? Companies like Noctua and BeQuiet an the other's whose names I forget put tons of time into optimizing axials for static pressure or airflow with the least noise, would be interesting to see what they could do with a centrifugal fan. 

[Guy Marshall]

Just now, Zando Bob said:

Now I lowkey want to get my hands on some old cheap blower cards and chop them up then jank together the finstacks and find different sized fans to see if there's a difference. Also I wonder if as much work has gone into optimizing centrifugal fans as axials? Companies like Noctua and BeQuiet an the other's whose names I forget put tons of time into optimizing axials for static pressure or airflow with the least noise, would be interesting to see what they could do with a centrifugal fan. 

Omg yeah same here! I don't have enough money unfortunately at the moment for that but someday! Can you imagine a D15 with a massive blower that would be so good! And knowing noctua it would be quiet enough to rest your head on and beat a few 360 mm rads lol

[Zando_]

Just now, Guy Marshall said:

Omg yeah same here! I don't have enough money unfortunately at the moment for that but someday! Can you imagine a D15 with a massive blower that would be so good! And knowing noctua it would be quiet enough to rest your head on and beat a few 360 mm rads lol

Just look at the NH-U12A. 120mm tower, matches the 140mm NH-D15. Noctua made very good fans and then built the finstack to work really well with those. If they engineered a very dense finstack to take advantage of the massive static pressure of a centrifugal fan, they could probs make something pretty awesome. I doubt it'd work as a CPU cooler though since the centrifugals work well being on the end of something and pushing air through it, but due to the shape of GPUs they're perfect for this. 

[Guy Marshall]

2 minutes ago, Zando Bob said:

Just look at the NH-U12A. 120mm tower, matches the 140mm NH-D15. Noctua made very good fans and then built the finstack to work really well with those. If they engineered a very dense finstack to take advantage of the massive static pressure of a centrifugal fan, they could probs make something pretty awesome. I doubt it'd work as a CPU cooler though since the centrifugals work well being on the end of something and pushing air through it, but due to the shape of GPUs they're perfect for this. 

Hmm that's a very good point about the fins they may look ugly to some people but they definitely perform! Can you imagine a focused tunnel where at one end is a centrifugal fan and through the entire tunnel is heatsink fins until you get to the edge of the case? Like a cylindrical heatsink of sorts, designed with the blower in mind.

 

Jay has proved that leaf blowers offer fantastic cooling due to the high static pressure, so in a pc case in an isolated tunnel away from the gpu it could work!

[Zando_]

Just now, Guy Marshall said:

Hmm that's a very good point about the fins they may look ugly to some people but they definitely perform! Can you imagine a focused tunnel where at one end is a centrifugal fan and through the entire tunnel is heatsink fins until you get to the edge of the case? Like a cylindrical heatsink of sorts, designed with the blower in mind.

 

Jay has proved that leaf blowers offer fantastic cooling due to the high static pressure, so in a pc case in an isolated tunnel away from the gpu it could work!

Longboi PC case when? I know Apple did something kind of like that with the trash can mac pro, they put one big fan on the top to suck air through everything and push it out. Putting everything in a series in front of a big blower would be a cool project. You'd need a lot of stuff to direct the airflow properly but it could be doable. Using a stubby GPU and ITX mobo so you can line up the finstacks would probs be a good idea. I doubt it'd get as compact as an ITX case with axials though, so it'd more be a "for fun" project. 

[Guy Marshall]

5 minutes ago, Zando Bob said:

Longboi PC case when? I know Apple did something kind of like that with the trash can mac pro, they put one big fan on the top to suck air through everything and push it out. Putting everything in a series in front of a big blower would be a cool project. You'd need a lot of stuff to direct the airflow properly but it could be doable. Using a stubby GPU and ITX mobo so you can line up the finstacks would probs be a good idea. I doubt it'd get as compact as an ITX case with axials though, so it'd more be a "for fun" project. 

Yeah definitely as I can guess the demand will be very low and only for people like us that like to tinker! It might work better on an open air test bench where the case isn't in the way, and then the cylinder heatsink covered to prevent air escaping can be as big as you can imagine, with the blower at one end and a hole at the other. Are we thinking too much into this?

[Zando_]

2 minutes ago, Guy Marshall said:

Yeah definitely as I can guess the demand will be very low and only for people like us that like to tinker! It might work better on an open air test bench where the case isn't in the way, and then the cylinder heatsink covered to prevent air escaping can be as big as you can imagine, with the blower at one end and a hole at the other. Are we thinking too much into this?

Probably, but it'd be interesting to see how cooling performance scales with static pressure. Is there a point at which pushing air through the finstack won't gain you any better temps (or so little for the increase in noise that it's not worth it). Or how dense can you make a finstack and still push air cleanly through it? 

[Guy Marshall]

1 minute ago, Zando Bob said:

Probably, but it'd be interesting to see how cooling performance scales with static pressure. Is there a point at which pushing air through the finstack won't gain you any better temps (or so little for the increase in noise that it's not worth it). Or how dense can you make a finstack and still push air cleanly through it? 

Exactly! It would have been very useful for the FX-9590 / 5960x times as they were hot! But now I guess we have the 9980 XE and 2990 WX to heat our warehouses instead.

 

There must be a point where it bottoms out but I can't imagine that point is realistically reachable seeing as TinyTomLogan did a video with extreme airflow on a H100i and, although we didn't see the real temps, I can imagine they were pretty darn impressive!

 

 

 

[Zando_]

@Guy Marshall Look issa centrifugal fan: https://www.anandtech.com/show/14494/colorful-has-a-singleslot-geforce-gtx-1660-ti-graphics-card

 

Instead of using a big one, they got a tiny one so they could make a single slot card. 

[Guy Marshall]

1 minute ago, Zando Bob said:

@Guy Marshall Look issa centrifugal fan: https://www.anandtech.com/show/14494/colorful-has-a-singleslot-geforce-gtx-1660-ti-graphics-card

 

Instead of using a big one, they got a tiny one so they could make a single slot card. 

Ooh I like! I would have thought that the open part at the end would reduce performance because there isn't a straight line for hot air to come out, instead there are two!