I was playing BF3 last night on max settings and the card in slot 1 reached 98C, while slot 2 only reached 62C. I guess it's normal for slot 1 to bear the brunt of the load but is it normal for such a huge difference in temps? Given my board, there's no space between the cards, so it's understandable that slot 1 (it's fans are up against the other card) will get hotter. Asus claims these cards are 2.5 slots wide but they're actually 3. All other slots on my board are covered by these two beasts.
Also, I've installed the optional 120mm fan housing that comes with the HAF X but I don't think I could fit in anything else, such as water cooling.
And the cpu fan was going ballistic too, up to about 1200 rpm (normally tops out at about 900 rpm). The cpu itself reached 59C. For comparison, with a single GTX480 on BF3 the cpu wouldn't exceed 52C and the card 82C.
My rig is:
Coolermaster HAF X
Coolermaster silent pro gold 1000W (modular)
i7-2600k @ 3.4GHz
Arctic Cooler Pro 13
8GB Corsair Vengeance CL8
OCZ Vertex 3 Max IOPS 120GB SSD (system)
WD 450GB Velociraptor
2 x Asus GTX580 (@782 MHz) SLI
I think I read somewhere that the cards are rated to 105C but can't find it now.
Take the side cover off while you are gaming and you will see a big drop in temps , all I can suggest is to put some side fans to help the hot air escape. They really do make a difference with multi gpus like yours.
The gpu fan speed is normally around 1,200rpm but goes up to 3,400 under load. It's very responsive.
The HAF X case has great airflow and the big side fan draws cool air in right onto the cards. The real problem is that the cards are touching, so the 2 gpu fans on the hot card are wedged up against the back plate of the second card.
I thought I'd try wedging something in between the cards to gently separate them. Hard plastic - like a thin toothbrush - will withstand 62C. Does that sound innovative or dumb? Otherwise I'd have to somehow pump in freezing air.