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Best airflow layout for internally exhausting videocards in SLI?!

Poll Results: With two internal-exhaust videocards, the side-fan should:

 
  • 46% (6)
    a) exhaust the hot air from the cards to the outside.
  • 53% (7)
    b) be an intake of cold air, blowing on top the cards.
13 Total Votes  
post #1 of 10
Thread Starter 
Hey guys,

I was wondering what is the best (or preferred) layout for case fans and etc to cool down two internally exhausting cards.

I know it depends a lot on the case (different cases have different airflow possibilities) but maybe the most common case style (here at OCN) has a side fan that could work as an exhaust or intake fan, right?

In my case I have two 14cm fans exhausting on top, and one 12cm exhausting to the back (to serve the cpu cooler). Intakes are a 14cm bottom fan and a 12cm frontal fan (blowing on the HDDs and SSD, as usual).
So, before I got a second videocard I kept the side fan (can only be 12cm) as an intake, to balance the intake/exhaust ratio, but after I went SLI I changed, without testing, the side intake to side exhaust.

It is giving me good temps (top card reaches 85C and bottom one reaches 81C with ambient temps at around 30C - summer ). That is after customizing the fan profiles for lower noise-higher temps on Afterburner (the cards are quiet enough, right now - around the same as a single 480gtx with a stock-cooler).

Anyways, since I have [2x12cm + 2x14cm exhaust] versus [1x12cm + 1x14cm intake], the rest of the intake is supplied passively through the mesh of the front panel (but that is only a single drive bay space and it aligned with the cpu cooler and immediately above the height of the top videocard).

So, what would you guys suggest (if anything) to improve it for summer?

Also, anyone out there with similar videocards (internally exhausting) can share their own fan layout?

post #2 of 10
Thread Starter 
Geez...
Someone, please throw me a biscuit here will ya?

woof
post #3 of 10
I'd use the side fan as intake since you already have enough exhaust fans in there that will create some positive pressure and cool down your video cards the exhaust fans will take care of the heat.

Also since you have a 140mm in the bottom that will send the hot air to the exhaust fans in the top
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post #4 of 10
Although my current system does not have a side fan my last case was an Antec 900 which did. It also ran the same system so it was a sandwich of GPUs. I've tested both intake and exhaust on that side fan and found that intake held the best results.

Although i'm no professional in the area my speculation tells me that the only case where an exhaust side fan would be more effective is if you included a duct that extended to the GPUs. Otherwise by blowing air over the GPUs it will effectively dissipate more heat, however may result in an increase in overall case temperature which would affect CPU/RAM/Northbridge etc.

It is also important to note that it is not necessary to balance out intake/exhaust. In most cases it is more beneficial to have more exhaust than intake.
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post #5 of 10
I have 2 Twin Frozr 580s in SLI in my HAF-X, I use a 166cfm 200mm side fan as intake and my video cards don't exceed 64C under load.
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post #6 of 10
+1 for side intake, i tried both intake and exhaust with my gtx295 (internal exhaust) and having the side as intake the vid card ran cooler, though only by 2 degrees. Every little bit helps.
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post #7 of 10
Thread Starter 
Quote:
Originally Posted by CloudCR View Post
I'd use the side fan as intake since you already have enough exhaust fans in there that will create some positive pressure and cool down your video cards the exhaust fans will take care of the heat.

Also since you have a 140mm in the bottom that will send the hot air to the exhaust fans in the top
Could be...
Thanks!


Quote:
Originally Posted by Enthusiast View Post
Although my current system does not have a side fan my last case was an Antec 900 which did. It also ran the same system so it was a sandwich of GPUs. I've tested both intake and exhaust on that side fan and found that intake held the best results.

Although i'm no professional in the area my speculation tells me that the only case where an exhaust side fan would be more effective is if you included a duct that extended to the GPUs. Otherwise by blowing air over the GPUs it will effectively dissipate more heat, however may result in an increase in overall case temperature which would affect CPU/RAM/Northbridge etc.
But, were your gpus exhausting outside or inside (reference cooler?)?

Quote:
Originally Posted by Enthusiast View Post
It is also important to note that it is not necessary to balance out intake/exhaust. In most cases it is more beneficial to have more exhaust than intake.
Agreed!


Quote:
Originally Posted by HWI View Post
I have 2 Twin Frozr 580s in SLI in my HAF-X, I use a 166cfm 200mm side fan as intake and my video cards don't exceed 64C under load.
20cm 166cfm fan!?
Nice! I wish I had one of those!
But the CM690 can't have that, un-modded at least, and I don't feel like modding.

Anyways, maybe I should give a try to intake again!
By the way, the cards are spaced by one slot (in case that might influence your choices).
post #8 of 10
Quote:
Originally Posted by Ulver View Post
But, were your gpus exhausting outside or inside (reference cooler?)?
Nah, all my cards are non-reference.
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post #9 of 10
For internally exhausting cards, there are generally 2 types:-
a. dumping heat uni-directionally (ie mainly dumping via the card's front. eg Nvidia reference GTX560 Ti)
b. dumping heat omni-directionally (eg aftermarket cooler like Zalman VF-3000)

Obviously, (a) is easier to be managed thermally well.
Generally speaking, if it is (a), then the side panel fan(s) should be 'intake' to supply fresh ambient air to the intake fan(s) of the card(s). Air supply from this direction will not run against the hot exhaust which is via the card's front.

However, if it is (b), then a side air supply will run against the hot air exhausting out via the card's top and this might bring to higher temperature. So, this has to be examined case by case.

For your MSI GTX580 Lightning, it is more or less a Twin Frozr II design. Due to the heatsink fins orientation and the shroud's skirting, its internal heat dump comes mainly via the card's front and only a smaller portion from the sides. This makes it more a case of (a) above.

As such, I suggest setting up the side panel fan(s) as intake.

Additionally, I recommend a 'top exhaust' approach to take care of most (if not all) internal dumped heat from the cards. I have explained this method before and a few members found it useful. Simply put, you setup the case fans so that the all hot exhaust is via the case top. This requires you orient the CPU cooler toward the top as well (in order to prevent hot air from cards being sucked by the CPU cooler fan). Read these threads for example:-

1) GTX580 Twin Frozr II SLI (in a HAF 932) - note post #12
http://www.overclock.net/computer-ca...ii-best-2.html

2) Asus GTX570 DirectCU II (in a CM 690 II Advanced) - note post #15
http://www.overclock.net/computer-ca...eed-fan-2.html

3) HD5970 (in a HAF 932) - note posts #16 and #28
http://www.overclock.net/air-cooling...w-chassis.html
Edited by windfire - 8/9/11 at 8:20pm
post #10 of 10
Thread Starter 
Quote:
Originally Posted by windfire View Post
For internally exhausting cards, there are generally 2 types:-
a. dumping heat uni-directionally (ie mainly dumping via the card's front. eg Nvidia reference GTX560 Ti)
b. dumping heat omni-directionally (eg aftermarket cooler like Zalman VF-3000)

Obviously, (a) is easier to be managed thermally well.
Generally speaking, if it is (a), then the side panel fan(s) should be 'intake' to supply fresh ambient air to the intake fan(s) of the card(s). Air supply from this direction will not run against the hot exhaust which is via the card's front.

However, if it is (b), then a side air supply will run against the hot air exhausting out via the card's top and this might bring to higher temperature. So, this has to be examined case by case.

For your MSI GTX580 Lightning, it is more or less a Twin Frozr II design. Due to the heatsink fins orientation and the shroud's skirting, its internal heat dump comes mainly via the card's front and only a smaller portion from the sides. This makes it more a case of (a) above.

As such, I suggest setting up the side panel fan(s) as intake.

Additionally, I recommend a 'top exhaust' approach to take care of most (if not all) internal dumped heat from the cards. I have explained this method before and a few members found it useful. Simply put, you setup the case fans so that the all hot exhaust is via the case top. This requires you orient the CPU cooler toward the top as well (in order to prevent hot air from cards being sucked by the CPU cooler fan). Read these threads for example:-

1) GTX580 Twin Frozr II SLI (in a HAF 932) - note post #12
http://www.overclock.net/computer-ca...ii-best-2.html

2) Asus GTX570 DirectCU II (in a CM 690 II Advanced) - note post #15
http://www.overclock.net/computer-ca...eed-fan-2.html

3) HD5970 (in a HAF 932) - note posts #16 and #28
http://www.overclock.net/air-cooling...w-chassis.html
Thanks for the input, man!
Will read through those threads ASAP
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