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Fan arrangement for SLI cards

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January 28, 2010 8:44:37 AM

Hi folks

I'm currently running 2x 260 GTXs in SLI, and it's getting a little toasty from time to time. My case has a 'fan flap' that allows me to use 2 fans directly over the cards, however I'm not sure what alignment to use for the fans.

Should I have both fans blowing hot air off the cards and directly out of the side of the case, or should they be pulling cool air in over them?

I've also heard that some people have one pointing in and one out, to circulate air directly over the top of the card.

I'd really appreciate any advice!

Boog
January 28, 2010 11:36:02 AM

Excellent advice. Thank you. The cards have also been overheating with the side off the case, but I assume that this was possibly because having the case shut and drawing air at a higher speed over the cards would actually cool the cards down faster than being open to the air entirely. Is this correct, or do I possibly have a bigger issue?
a c 271 U Graphics card
January 28, 2010 9:13:53 PM

The temps of my cards are lower if I have the side fans on my case set as exhausts rather than inlets, as in drawing air away from the cards rather than blowing air onto them.
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a c 227 U Graphics card
January 28, 2010 10:30:26 PM

Standard case design is based upon the window fan blowing in....of course not everyone follows standard practice and every case like this will be different. Considering the fact that all the GTX's I have seen have a ducted exhaust out of the case, I gotta go with having teh side fan blowing in as you prolly have plenty of hot air going out and need some extra "inflow" to balance what's already going out.
a c 271 U Graphics card
January 29, 2010 10:33:01 AM

Quote:
Then you dont have proper air flow to begin with. The side fans are for intake, as is the top. The front is also for intake. The rear is supposed to be all exhaust. This creates a push/pull effect. Having air blowing out the side negates the push pull effect because you have 2 exit points and only one entrance.

To the OP, there's always going to be someone out there that says they do soemthing backwards and it works better, but I would suggest you do it the proper way.

Just as you have spent time figuring out the ATIKMDAG issue, I have spent time playing about with the fans on my case which has more than two exit points by the way.
a b U Graphics card
January 29, 2010 11:56:51 AM

I give a shot at this. Seeing you have 2 side fans and supposing you have a top or back fan my configuration would be:

Both side fans to push air inside and the top/back fan to exhaust the warm air generated.

The cards will generated heat which will be partially eliminated by their own exhausts and the rest or the air will rise. That air will be caught by the back or top fan and exhausted outside. From an airflow point of view it is better to have multiple intakes and fewer faster/bigger exhaust fans.
a c 271 U Graphics card
January 29, 2010 12:00:27 PM

Quote:
Your case has more than 2 exit points? Is this a home-built case? How can a case have 2 backs?

If you read the instructions on the case, it tells you to have the top fan as intake, the side fan as intake, the front fans as intake and the rear fans as exhaust. If you have more than one exit point then that's screwing up your push/pull airflow.

First off your definition of exit point only being possible at the back is 'odd' as fans move air if the fan is set as an exhaust then the air will exit the case at that point regardless of whether it is at the top, bottom, side, front or back so why would I need instructions? not that there were any.
a c 216 U Graphics card
January 29, 2010 2:29:16 PM

The default configuration of the Antec 902 has an exhaust out the back and out the top. They have two fans in the front of the case, and room to mount a fan over the video cards on the side panel.
a c 271 U Graphics card
January 29, 2010 2:33:45 PM

So at what point have I or the OP mentioned a particular make and model of case? and if an Antec 300 or 900 is the same as every other case out there then there is no point in buying one as any case that's cheaper will be the same.
January 29, 2010 3:57:55 PM

I had a similiar problem with my Thermaltake Xaser III case. I had 2 overclocked MSI GTX 260s in SLI. I put 2 high speed, low noise (they exist) 120s over the card.

I would recommend intake in the front (which also probably helps your HDD as well) and sides, exhaust on the top and the back.

What kind of cpu cooler do you have, what kind of case, and what size/power of fans? These can change the fan setup...

For example, my case actually has 3 120 intakes on the side and 5 exhaust fans (2 80s in front, 2 80s in back, 1 80 on top). It sounds kinda weird but the 3 120s bring in (1 over my ram) about 240 cfm. I noticed that they were so powerful that they pushed air towards my intakes in the front rendering them useless. So I flipped them around as outtakes. Air comes in the side and is pulled out the top, the front, and the back. It dropped my temps around 2 C on my components from the traditional intake front fan set up.

You can also play around with the fan set up and see what does best. To test temps I ran the computer idle for a while and then started prime95 for 30 minutes and checked. I then changed the fan set up and repeated until I got the lowest setup.
a c 271 U Graphics card
January 29, 2010 4:12:55 PM

thegreathuntingdolphin said:
I had a similiar problem with my Thermaltake Xaser III case. I had 2 overclocked MSI GTX 260s in SLI. I put 2 high speed, low noise (they exist) 120s over the card.

I would recommend intake in the front (which also probably helps your HDD as well) and sides, exhaust on the top and the back.

What kind of cpu cooler do you have, what kind of case, and what size/power of fans? These can change the fan setup...

For example, my case actually has 3 120 intakes on the side and 5 exhaust fans (2 80s in front, 2 80s in back, 1 80 on top). It sounds kinda weird but the 3 120s bring in (1 over my ram) about 240 cfm. I noticed that they were so powerful that they pushed air towards my intakes in the front rendering them useless. So I flipped them around as outtakes. Air comes in the side and is pulled out the top, the front, and the back. It dropped my temps around 2 C on my components from the traditional intake front fan set up.

You can also play around with the fan set up and see what does best. To test temps I ran the computer idle for a while and then started prime95 for 30 minutes and checked. I then changed the fan set up and repeated until I got the lowest setup.

:o  You changed something and saw an improvement, but that's impossible according to some around here. :sarcastic: 
a c 271 U Graphics card
January 29, 2010 4:50:41 PM

Quote:
I'm not going to argue with you. If you read the instructions that come with the Antec 300/900, that's how the instructions say to do it and it works for me so hey.

If you think doing it another way is better go for it. I tend to follow what the designers of the case say is the best way and they specifically say the side fan is supposed to blow IN to cool the video cards and quickly get's sucked out the back.


I'm pretty sure you were the one who first mentioned the Antec's.
!