Games Freezing on high end rig

Im having this problem with bf3 and crysis 3 where I can play for like an hour but then the games will freeze and I have to exit out via alt + ctrl + delete. My drivers are up to date running on win 7 basic.

System specs:
16gb ram
dual sli 680's
4 fans
950w psu
pz77-v
i5-3570

Any help would be nice.

I should add that its overclocked to 4ghz

EDIT: sorry it double posted