Display Freezes in some games, works pefectly the rest of the time

So, I have been having problems recently with my GPU (I believe).

What happens is in some games (not all games) after a while (a few hours at least usually) the display freezes. the sound keeps playing which makes me assume the rest of the PC is functioning. This stays this way for about 10 seconds and then the sound stops as well, which makes me assume the rest of the PC has stopped working. at this point I reboot the computer manually (hard reset).

The strange part is this only happens in games, and it only happens with some games. It happens with Deus Ex: HR, and Recettear from my experiences, but does not happen in Minecraft or Team fortress 2 for example. I can't find a connection between any of the games, so I have no idea whats going wrong.

I started troubleshooting by downgrading my drivers from beta 12.2 to 12.1 (stable). this has not worked.

Any other ideas to what could be wrong? I think it may be the BIOS (possibly?) because I am on a beta BIOS, but I cant downgrade that and I need it in beta anyway, because it fixes the problems I was having before, with my CPU.

EDIT: see "system specs" (under my username) for my system specs

PS: Besides that random weird crash/freeze during some games, my system is perfectly stable.

Nevermind, solved, it seems it was my "personalize" settings were corrupted, so when my screensaver tried to activate during a game, instead of doing what it normally does, it crashed my computer.