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A Primer: HD6990's Heat Management Within a Typical Case

post #1 of 2
Thread Starter 
HD6990's reference cooling involves a central fan intaking cool air and vents exhausting at card's front and card's rear (see pic 1 below). Rear heat dump outside the case poses no problem. However, heat dump at the front requires careful thermal management. I have looked through all the reviews listed here (http://www.overclock.net/hardware-news/850154-official-radeon-68-0-69-0-a.html) and none mentions about the computer case used (actually 2 reviewers said they used a Test Bench).

So, I did a little thinking and, using the popular HAF 932 as a typical air cooling case, I reckon there are 5 possible escape routes for the hot air exhausted from the card's front.

These escape paths are through:- (see pic 2)
1. front Fan A
2. top Fan B
3. rear Fan C
4. bottom Fan D
5. side panel Fan E

Each escape route has its Pros and Cons:-
1. front Fan A
Pros: By CM's default, Fan A is an intake fan. If it is reversed as an exhaust, this setup has 2 strong benefits. First is that the hot air takes a very short path to get outside of the case. Second is that the hot air flow does not need to change direction. Horizontally it is exhausted out of the card, so it will horizontally exhausted out, meaning high efficiency.
Cons: air intake for the whole case is reduced as the Fan A is now reversed as exhaust. And, hot air might warm up some HDDs.

2. top Fan B
Pros: Fan B is an exhaust fan by CM's default. No reversal setup is needed.
Cons: 230mm Fan B is a high CFM fan but spins rather slow, resulting in low air pressure. Therefore, it needs to spin faster in order to create enough pressure to suck the hot air up. Or else, the hot air will be sucked into the CPU heatsink fan, which is obviously a highly non-desirable situation. However, if it spins too fast, it will certainly disrupt the good air flow into the heatsink fan, in addition to bringing more noise and vibration.

3. rear Fan C
Pros: same as Fan B
Cons: Fan C will need to spin faster so that the hot air is sucked to it rather than being sucked by the heatsink fan. And, the hot air flow path needs to make a 180 degrees U-turn from the card's front to reach this fan, meaning not very efficient.

4. bottom Fan D
Pros: with a 120mm fan setup here as an exhaust, hot air can be extracted fairly efficiently.
Cons: this fan acts oppsite to the card's intake fan (blue arrow), leading to a competition of fresh air.

5. side panel Fan E
Pros: not much
Cons: the default intake needs to be reversed, substantially reducing fresh air intake to the card and to the entire case/motherboard

As one can see, none of the above solutions is good enough.

Instead, I propose:- (see pic 3)
1. replacing top stock 230mm fan by two 120mm fans for exhaust. These 2 fans will spin at a faster rpm to create an upward draft for the extracting hot exhausted air from the CPU and the 6990.
2. adding a bottom 120mm fan for intake. This fan supplies fresh air to the 6990 and the PSU.
3. re-orienting the CPU heatsink, pointing upward for exhaust.
4. front Fan A remains as intake. Its relatively lower rpm will not generate air pressure high enough to push hot air back into 6990 and yet it has enough CFM to cool the HDDs
5. side panel 230mm fan is important to provide enough fresh air to the CPU. If more air is needed, it can be replaced by 120mm fan(s).

This is certainly neither the only solution nor the perfect optimal setup. However, I hope this can be useful for a proud owner of the 6990 to build his own ideas upon this little primer.
post #2 of 2
IMO adding some powerful 120mm fans for the side panel would be the best option on the 6990. Intaking colder air from the outside to go through the card would lower temps a bit. Though IMO the best option if you can afford it is to find a good aftermarket cooler that would fit it if any, or better yet water cooling. It'll probably be loud and run warm, but I figure nowhere near as bad as say a 470/480.
Edited by yoshi245 - 3/8/11 at 6:22am
Main
(14 items)
 
  
CPUMotherboardGraphicsRAM
2500k ASROCK P67 Extreme 4 Gen3 Sapphire 7950 Dual X 8GB GSkill Ripjaws@8-9-8-23 1600 
Hard DriveOptical DriveCoolingOS
GSKILL Phoenix Pro 120gb SSD, 3x 1.5TB hdd, 2tb Samsung 24x dvd-rw Thermalright Silver Arrow with 3 TY-140 fans Win7 X64 
MonitorKeyboardPowerCase
Sharp 40" Aquos LCD TV as main monitor 2 ASUS 2... Thermaltake TT eSports Meka G1 Corsair TX750 HAF 932 
MouseMouse Pad
G400 Artisan Hien VE L Samurai Black 
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Main
(14 items)
 
  
CPUMotherboardGraphicsRAM
2500k ASROCK P67 Extreme 4 Gen3 Sapphire 7950 Dual X 8GB GSkill Ripjaws@8-9-8-23 1600 
Hard DriveOptical DriveCoolingOS
GSKILL Phoenix Pro 120gb SSD, 3x 1.5TB hdd, 2tb Samsung 24x dvd-rw Thermalright Silver Arrow with 3 TY-140 fans Win7 X64 
MonitorKeyboardPowerCase
Sharp 40" Aquos LCD TV as main monitor 2 ASUS 2... Thermaltake TT eSports Meka G1 Corsair TX750 HAF 932 
MouseMouse Pad
G400 Artisan Hien VE L Samurai Black 
  hide details  
Reply
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