PC freezing, monitor going to standby.

Hi,

SYSTEM;
Win 7 64x - Latest updates
GB P67A-UD3 mobo
i5-2500k
HD6950
XMS3 4gig
Corsair 750W PSU
All stock.
Drivers up to date for most part.

My PC has recently developed a problem. When playing games, after a while the game will freeze, the monitor goes to stand-by mode and the PC becomes unresponsive. The fans will speed up and down as if the PC had been rebooted.

I have to reset via the button to get out of this state. On reboot into windows, it will say 'Windows has recovered from an unexpected shutdown...' (Or something like that). It has generated a minidump and says the cause was a BSOD.

Now, how do I go about troubleshooting this problem? Is it hardware/software? Here's what I've managed to pull from windows debugging, don't know how to set all the symbol nonsense right.

ADDITIONAL_DEBUG_TEXT:
You can run '.symfix; .reload' to try to fix the symbol path and load symbols.

FAULTING_MODULE: fffff80002e66000 nt

DEBUG_FLR_IMAGE_TIMESTAMP: 5154e9d9

FAULTING_IP:
atikmpag+ab38
fffff880`042acb38 48895c2408 mov qword ptr [rsp+8],rbx

DEFAULT_BUCKET_ID: GRAPHICS_DRIVER_TDR_FAULT

CUSTOMER_CRASH_COUNT: 1

BUGCHECK_STR: 0x116

CURRENT_IRQL: 0

Any help would be appreciated. It says graphics driver fault, but the games been running 100% ok for weeks on the same driver.

Thanks.