Hi,
Does it really run that hot then? You might want to try setting up a custom fan profile for the default clock first as I find the stock fan profile on NV cards is quite slow.
If the temps really are that high or the noise of the fan on a more agressive fan profile is too much then you could down-clock it.
I'd suggest something like 800mhz core @ 1000mv with just 2000 on the memory might be a good starting point. The reason I say this is because 1000mv is what my 2nd 570 needs to be stable at 800mhz.
For testing I find 3D Mark Vantage to be a good starting test, followed by 3D Mark '11 which is slightly more stressful and, finally, Heaven 2.5 is pretty good. However I still find that Crysis 2 with DX11 and Texture packs pushes things harder than any of the above during a gaming session.
So, build your way up getting progressively more stressful on each test - or just fire up Crysis 2 right away lol.
If you prove to be STABLE, then you can try lowering the GPU vCore a notch - note a "notch" is around 7 or 8mv, if you try to adjust
less than this you'll likely see Afterburner jump to the prior voltage...it's odd like that, so keep an eye on it.
If you prove to be UNSTABLE, then you can either bump the GPU vCore up a notch OR chose to lower the core clock even more.
Either way, if you hit a stable point you can always lower clocks (and vCore) some more to get things running even cooler.
If you get a 2nd card it's default Vcore (for it's factory OC) may well be different - my two GTX 570's are about 35mv different at stock settings to start with. You can try (like I did) adding, or in your case removing, the same amount of GPU vCore to under clock the 2nd card the same. As you should already know the stable settings for your first card, any instability
should be due to the 2nd card.
Best of luck and keep us posted how you get on
Scoob.