Are gfx cards upside-down?

Devrij · 22 Nov 2012 at 12:28

With all the thinking about cooling I've been doing lately, I keep asking myself why the PCB has the chip on the bottom, and why the cooler has to work against the natural flow of heat. Why don't we have the cooler on top blowing air upwards?

The only reason I can imagine is that the fans work better in push than in pull configuration, and so the fans are pushing upwards through the heatsink (albeit into the resistance of the PCB). Has anyone else got any theories or knowledge in this matter?

tom_e · 22 Nov 2012 at 12:33

It's a legacy thing iirc I can't remember the exact reasoning behind it but there was a reason back in olden times.

seabiscuit · 22 Nov 2012 at 12:54

It was one of the "advantages" of the BTX form factor was that it put cards the right way up. About the only advantage of it though.

Devrij · 22 Nov 2012 at 13:11

seabiscuit said:
It was one of the "advantages" of the BTX form factor was that it put cards the right way up. About the only advantage of it though.

Was this mounting your mobo on the other side of the case, or different altogether? And what's stopping them from just flipping the connector round so the PCB sits the right way up? Presumably it would foul the CPU heatsink on some boards, but not all.

The impression I'm getting is that it's some ridiculous legacy thing that needs changing, but no one wants to make the jump for fear of losing sales due to incompatibility?

Jakus · 22 Nov 2012 at 13:43

Yup,, they are all idiots

, totally cracks me up when they talk about Vapour chamber coolers etc then mount them upside down !

Another design cockup is having the PSU at the bottom and mounting the motherboard in the hottest part of the case... the top back corner !!

I always where possible have fans blowing away from boards not blowing hot air at them ! generally you will loose a little efficiency because you are pulling stagnant air through the cooler but board temps will be less.

Rusty0611 · 22 Nov 2012 at 13:48

Well if you went multi GPU one would be blowing heat straight into a wall of PCB of another card. Just guessing but that might cause a problem. If not then who knows

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dave_beast · 22 Nov 2012 at 14:06

RV02 got it right.

Devrij · 22 Nov 2012 at 14:10

Rusty0611 said:
Well if you went multi GPU one would be blowing heat straight into a wall of PCB of another card. Just guessing but that might cause a problem. If not then who knows .

Is that not what happens now? Only now that air then rises back towards the heatsink it just left.

@Dave, I agree that the Raven is a good solution to this problem. It does make a lot of sense. Why don't all cases do this?

Rusty0611 · 22 Nov 2012 at 14:18

Devrij said:
Is that not what happens now? Only now that air then rises back towards the heatsink it just left.

Slightly different.

Now, you've got the bottom card like normal blowing its air out cleanly and sucking in cool air. The top one recycles the hot air from the bottom one.

With the fans turned round the bottom card would be blowing air into a wall (the top PCB) where it can't be removed and the top card would be running as it would before as well i.e. drawing in the hot air when it gets blown round.

squarebutt · 22 Nov 2012 at 14:24

Mine blows it into a wall anyway, the sound card. Theres only 1 slot for this, the other one being covered by my 2 slot deep gpu, and the gpu either sits straight above it, or down the case in the area of the psu. None of this was mentioned when I bought the P6T DL.

Jakus · 22 Nov 2012 at 15:49

Before you even start worrying about the incidentals you need to think about servicing the case air fast enough to deal with, 500-1000 watts depending on setup, especially GFX card type.

It does not matter which way you blow "hot air " around it's not going to be much use for cooling

Devrij · 22 Nov 2012 at 16:09

JAKUS said:
Before you even start worrying about the incidentals you need to think about servicing the case air fast enough to deal with, 500-1000 watts depending on setup, especially GFX card type.

It does not matter which way you blow "hot air " around it's not going to be much use for cooling

Point well made, but we'll assume for these purposes that we have good case cooling. I suspect mine is very wonky though, due to some oddly placed intake fans on the NZXT phantom. There are two for cooling the HDDs and pushing that air out the other side (rather than pushing it into the main body of the case), but the front intake crosses paths with these so I suspect it does bugger all to cool the main case. That leaves one 200mm roof exhaust and one 120mm rear exhaust. Perhaps I need to get a smaller CPU heatsink so I can fit a side fan on to blow some cold air at my GPU

Jakus · 22 Nov 2012 at 18:05

Proper case layout here...

http://www.anandtech.com/show/5556/lian-lis-pc90-the-hammer-strikes-hard/2

Hardisks and housings behind the front fans destroy smooth cool air flow into the case.

Good to see your putting a bit of effort into this interesting subject, which is so misunderstood by most.
Have a play and see if you can remove obstructions, including fans, initially you only want case fans on the perimeters of the case either inducting or expelling air.

Zero Pope · 22 Nov 2012 at 18:09

My Bitfenix case has the GPU at the top with the fan pointing up, out of a top vent.

Devrij · 22 Nov 2012 at 19:17

JAKUS said:
Proper case layout here...

http://www.anandtech.com/show/5556/lian-lis-pc90-the-hammer-strikes-hard/2

Hardisks and housings behind the front fans destroy smooth cool air flow into the case.

Good to see your putting a bit of effort into this interesting subject, which is so misunderstood by most.
Have a play and see if you can remove obstructions, including fans, initially you only want case fans on the perimeters of the case either inducting or expelling air.

I'm tempted to experiment with some unorthodox configs.

I'm thinking maybe putting an intake roof fan at the front, leaving the roof exhaust behind the CPU cooler with the rear exhaust. Maybe putting a 120mm intake in the optical bays to feed the CPU cool air.

Then for the gpu have the low front intake (maybe move the HDD cage) and have a side panel exhaust for the gpu. Then I would have 2 seperate cooling systems for gpu and CPU.

No idea how it would work in practice. Atm most of my gpu heat seems to be coming out the rear exhaust.

Orcvader · 22 Nov 2012 at 19:36

I've always wondered this as well, was thinking of getting a case like the RV02 but due to space I really need a super compact case as well. Maybe I should mod my case one day...

Jakus · 22 Nov 2012 at 20:29

Devrij said:
I'm tempted to experiment with some unorthodox configs.

I'm thinking maybe putting an intake roof fan at the front, leaving the roof exhaust behind the CPU cooler with the rear exhaust. Maybe putting a 120mm intake in the optical bays to feed the CPU cool air.

Then for the gpu have the low front intake (maybe move the HDD cage) and have a side panel exhaust for the gpu. Then I would have 2 seperate cooling systems for gpu and CPU.

No idea how it would work in practice. Atm most of my gpu heat seems to be coming out the rear exhaust.

Well you don't want to be fighting nature (hot air rises) 2 cooling circuits sounds a good idea, split the case with some cardboard to keep them separated.
Your GFX card is the villain, its dumping 3x the heat of you cpu,that's the area you have to work on, I would put a 120mm fan in the bottom of the case with a 5" duct to feed the fans.

Devrij · 23 Nov 2012 at 07:43

That's why I thought it was a bit unorthodox. Although drawing cool air downwards shouldn't be fighting much, especially as the flow of air pushes most of the hot air to the rear of my case before it gets as high as my CPU heatsink. That's my theory anyway!

My worry, if I were to compartmentalize the two systems, would be the extra wattage from my GFX card wouldnt be exhausted fast enough, and my CPU would be the only really beneficiary. It's really my gpu I want to cool down, but reducing the hot air flowing into my CPU heatsink would certainly be nice.

I'll definitely see if I can add a 120mm to the bottom of the case, I hadn't considered that!

bru · 23 Nov 2012 at 08:36

I think it all stems back to when cases were the horizontal desktop style rather than the vertical tower style we have now. Of course back when desktop style cases were all the rage we didn't have these mammoth heat producing gpu's to contend with.

Devrij · 23 Nov 2012 at 09:03

bru said:
I think it all stems back to when cases were the horizontal desktop style rather than the vertical tower style we have now. Of course back when desktop style cases were all the rage we didn't have these mammoth heat producing gpu's to contend with.

Good point, and we used to put our monitors... ON them :eek: