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cards with gpu on other side?

T

thursday

Weaksauce
Joined
Sep 4, 2003
Messages
122
I've been seeing threads on aftermarket heatsinks for the 8800 gt and have been wondering why there aren't any graphics cards with the GPU on the bottom side, so that when installed, it faces up? wouldn't that be a better thermal design? Upside-down heatsinks and heatpipes wrapping around a card looks a little ridiculous.

Who else feels we need a new spec.. like the failed BTX?
 
I don't really think it would matter which side of the card the GPU is on. If anything I would speculate that the current design is better (take colder air from bottom of case, blow it on GPU, and it rises up to the exhaust fan), as otherwise GPUs will be sucking in air that came off of the toasty CPU.

Besides, the heatpipes that wrap around the card do so to get more surface area, not because it is better to cool the GPU from above the card than below.
 
kllrnohj said:
I don't really think it would matter which side of the card the GPU is on. If anything I would speculate that the current design is better (take colder air from bottom of case, blow it on GPU, and it rises up to the exhaust fan), as otherwise GPUs will be sucking in air that came off of the toasty CPU.

Besides, the heatpipes that wrap around the card do so to get more surface area, not because it is better to cool the GPU from above the card than below.
Click to expand...

you contradicted yourself there. the CPU exhaust would be rising/exiting through the case exhaust fan while the GPU air (with the OPs gpu idea) would be right in the airflow of the case (for most cases anyway)... cooling it even more.

it could vary a lot though by different case designs.
 
You may be right..
and at least new gen cards are running a little bit cooler/efficient than previous ones, so I guess ATX will be sufficient for a while.
 
motox33 said:
you contradicted yourself there. the CPU exhaust would be rising/exiting through the case exhaust fan while the GPU air (with the OPs gpu idea) would be right in the airflow of the case (for most cases anyway)... cooling it even more.

it could vary a lot though by different case designs.
Click to expand...

Not really because your CPU fan is blowing air towards the motherboard, which will then spread outwards, not only upwards. The GPU fan will also be sucking air in, which will more than negate the affect of hot air rising. Besides, if the GPU is on top it can't exhaust the air out the back of the case in dual-slot cards.

Regardless, if you measured air temperature below the GPU and above the GPU I'm fairly certain the air above the GPU is warmer (CPU, power circuitry, etc... all contributing heat), which would indicate that the current design is better - if only marginally. Either way, there won't be any major difference with the GPU on top vs. on bottom. The OP seems to be under the impression that upside down heatsinks (not that the distinction of it being upside down matters - heatsinks aren't orientation sensitive) perform worse - which of course isn't true.
 
I've always wondered this myself. Especially back when almost all cases were ATX style, where the "cool" looking part of the card faced down. So if you had a side window, you couldn't see it. Why put such cool graphics and looks on the side of the card that you can't even see?

Regretfully, I doubt at this point that anything is going to change, so no luck for the "bling" effect on cases with side windows.
 
Exactly, they spend alot of time trying to make graphics cards look great, but no one can see them...
 
I don't have this problem as I have a Lian Li case, were my mobo is upside down so all my PCI cards face up :D
 
Okay folks, I'm going to clear up one major misconception among you: heat only rises in air, and that's because the temperature differential causes air currents. The air currents carry the warmer air higher.

Within solid materials, the effects of gravity on heat flow are virtually nil. The heat conducts in all directions to all edges of the card, and the card, combined with the heat sink, conducts the heat to the surrounding air. In other words, just mounting the GPU on top of the card won't make an appreciable difference in cooling.

The whole purpose of the ATX specification putting cards in upside-down was to create a separate cooling zone from the processor. Right now, air comes in from the front, and is split between the processor cooling space and the card cooling space. Sure, if you want, you can mix the two, but don't expect the results to be "better." Mashing multiple components into a smaller cooling space makes for less efficiency - either the air temperature must be higher, or the airflow must be faster, but something has to handle that extra heat in the same volume of space.

There's really nothing stopping you turning the cards "right side up," but the benefits just don't exist.
 
Though, Im always disappointed when I buy a new card only to see the backside while the fancy designs on the front face the floor.
In terms of visual appeal, Im sure many of us would love a top facing videocard.
 
Wait until you all try to put a fairly large CPU cooler and a fairly large GPU cooler together in this configuration. Well hope you all have fun!
 
defaultluser said:
Okay folks, I'm going to clear up one major misconception among you: heat only rises in air, and that's because the temperature differential causes air currents. The air currents carry the warmer air higher.

Within solid materials, the effects of gravity on heat flow are virtually nil. The heat conducts in all directions to all edges of the card, and the card, combined with the heat sink, conducts the heat to the surrounding air. In other words, just mounting the GPU on top of the card won't make an appreciable difference in cooling.

The whole purpose of the ATX specification putting cards in upside-down was to create a separate cooling zone from the processor. Right now, air comes in from the front, and is split between the processor cooling space and the card cooling space. Sure, if you want, you can mix the two, but don't expect the results to be "better." Mashing multiple components into a smaller cooling space makes for less efficiency - either the air temperature must be higher, or the airflow must be faster, but something has to handle that extra heat in the same volume of space.

There's really nothing stopping you turning the cards "right side up," but the benefits just don't exist.
Click to expand...

Heatpipes that use phase change require the heat source to be on the bottom so the vapour can rise to the top (requires gravity below) where it is cooled to a liquid by the fins and then drops back down to the bottom again.
A phase change heatpipe will still work through conduction if it is not the right way up but it will not be as effective.

http://www.madshrimps.be/?action=getarticle&articID=107
"In heat-pipe cooling, copper tubing is filled with a liquid. The tubes are then built into an existing heat-sink design, or a design is built around them, regardless there's now the added benefit of phase-change. The process is implemented by means of allowing the lowest gravitational point of the tubing (where the water would naturally settle) to be incorporated into the base of the heatsink. The point where the processor's surface would be in closest proximity. The CPU's original kinetic energy (heat) conducts through the TIM, and then seeks the cooler heat-sink base, now infused with the heat-pipes. That heat is now conducted to the liquid within. Again the heat (kinetic energy) seeks the colder element, in this case the liquid. As that liquid now absorbs the kinetic energy, or heat (its molecules speed up) it expands and vaporizes. This vaporized liquid (or phase-changed (liquid > gas)) rises in the heat-pipes, taking with it the kinetic-energy (heat) from the processor. As the vapor rises in the pipes to the area where the fan is blowing air down, around, and over those pipes/fins, the gas within undergoes yet another phase-change. The kinetic energy is again released, from the gas, through the copper tubes, and the vapor then condenses to liquid form. As the liquid is cooled even further by the cold air being blown over the tubing, it begins its return to the base of the heat-pipes, via gravity, to begin the process all over again"
 
Nenu said:
Heatpipes that use phase change require the heat source to be on the bottom so the vapour can rise to the top (requires gravity below) where it is cooled to a liquid by the fins and then drops back down to the bottom again.
A phase change heatpipe will still work through conduction if it is not the right way up but it will not be as effective.
Click to expand...

Who said anything about heat pipes?
 
Nenu said:
Heatpipes that use phase change require the heat source to be on the bottom so the vapour can rise to the top (requires gravity below) where it is cooled to a liquid by the fins and then drops back down to the bottom again.
A phase change heatpipe will still work through conduction if it is not the right way up but it will not be as effective.

http://www.madshrimps.be/?action=getarticle&articID=107
"In heat-pipe cooling, copper tubing is filled with a liquid. The tubes are then built into an existing heat-sink design, or a design is built around them, regardless there's now the added benefit of phase-change. The process is implemented by means of allowing the lowest gravitational point of the tubing (where the water would naturally settle) to be incorporated into the base of the heatsink. The point where the processor's surface would be in closest proximity. The CPU's original kinetic energy (heat) conducts through the TIM, and then seeks the cooler heat-sink base, now infused with the heat-pipes. That heat is now conducted to the liquid within. Again the heat (kinetic energy) seeks the colder element, in this case the liquid. As that liquid now absorbs the kinetic energy, or heat (its molecules speed up) it expands and vaporizes. This vaporized liquid (or phase-changed (liquid > gas)) rises in the heat-pipes, taking with it the kinetic-energy (heat) from the processor. As the vapor rises in the pipes to the area where the fan is blowing air down, around, and over those pipes/fins, the gas within undergoes yet another phase-change. The kinetic energy is again released, from the gas, through the copper tubes, and the vapor then condenses to liquid form. As the liquid is cooled even further by the cold air being blown over the tubing, it begins its return to the base of the heat-pipes, via gravity, to begin the process all over again"
Click to expand...

Thats not entirely correct, as there are plenty of heatsinks that use heat pipe tech, and do not adhere to those principles. One example is the HR03 GPU heatsink, which can be mounted wrapped around the card, or the other way. Either fins above the GPU or below. By your principles, one way would not work at all since the fluid would stay away from the heat source once condensed, if the fins were mounted below the GPU.

The liquid generally returns to the heat source via capillary action, there is generally some kind of mesh in the tube for the liquid to cling to, while the vapor goes up through the middle of the tube.
 
Note I said "heatpipes that use phase change", implying that not all heatpipes use phase change but the ones that do were being discussed.

I was pointing at that it depends on the heatsink used whether you can ignore its orientation.
A quite useful point methinks.
 
kllrnohj said:
Who said anything about heat pipes?
Click to expand...

Last time I looked at my GPU cooler it had heatpipes on it.
As we are discussing the orientation of the GPU on the card, this directly affects where you can place the heatsink and its orientation too.
Heatpipe heatsinks that use phase change will perform better with the heatsink base at the lowest point.
 
I faintly remember that there used to be an Asus card that had the GPU on the other side of the card. I think it was based on the NVidia 6000 series.

It must not have been popular since I only saw it while browsing through NewEgg.
 
kllrnohj said:
Not really because your CPU fan is blowing air towards the motherboard, which will then spread outwards, not only upwards. The GPU fan will also be sucking air in, which will more than negate the affect of hot air rising. Besides, if the GPU is on top it can't exhaust the air out the back of the case in dual-slot cards.

Regardless, if you measured air temperature below the GPU and above the GPU I'm fairly certain the air above the GPU is warmer (CPU, power circuitry, etc... all contributing heat), which would indicate that the current design is better - if only marginally. Either way, there won't be any major difference with the GPU on top vs. on bottom. The OP seems to be under the impression that upside down heatsinks (not that the distinction of it being upside down matters - heatsinks aren't orientation sensitive) perform worse - which of course isn't true.
Click to expand...
Thank you. I didn't realize heatsink orientation didn't matter as much as airflow around them :eek:. I guess a better approach would be a case design like the Apple G5 and a few other PC cases that have separate chambers.

SockMan! said:
I faintly remember that there used to be an Asus card that had the GPU on the other side of the card. I think it was based on the NVidia 6000 series.

It must not have been popular since I only saw it while browsing through NewEgg.
Click to expand...
ah, found a review of one in case anyone is interested:
http://www.hardwarezone.com/articles/view.php?cid=3&id=1997
and like others have stated, there won't be enough room for a large heatsink on both the GPU and CPU with that configuration and on current ATX motherboards.
 
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