KnightNight said:
It's more than likely due to something overheating.
I'm not an expert but if you've never fully pushed your GPU's which it's kinda unlikely that you have, then they could be overheating. Try pushing them up to a higher fan setting or something. It could also be you CPU overheating so check that too.
Although it will be impossible to test now because the beta has ended make sure it doesn't happen with other games just in case.
That could be the case, however I keep the statistics of maximum temperature reached on both GPUs and the CPU and, as mentioned before, in sustained game-play nether even touch the 70C mark (2 hours of BF3 and 2 hours of PS2). The 'Twin Frozr III' GPU cooler was the best ,already equipped, air based cooler for the 570 and the temps show that. My Coolermaster Hyper 212 Plus is in push/pull configuration as well. My rig is arguably at its full 'air' cooling potential.
Now it is quite possible that there may be some part some where overheating, but I find that to be the least likely do to: extreme case ventilation and it may have to do with the Crisis 3 Beta not having 'very' good SLI support.
As for pushing my GPUs... I was able, at one point, to push one of them to 1Ghz with just the equipped cooler but that was on the week that it arrived and the overclock was only 'stable' through one run of 3D Mark 11. I have yet to push the SLI configuration to its full potential on air but I would LOVE to see how they do underwater.
BUT this topic is now irrelevant seeing as the Beta is now over and it should probably be closed.