Before Christmas, I would have a Win Power 650W PSU, and a Radeon 5450 graphics card, and playing SW:TOR would be pretty much unbearable.

Now I have upgraded to a Cooler Master 550W, and a XFX Radeon HD 6770, and after an hour or so my screen would freeze, and I could still hear the music, then the screen would go black and I would get a BSOD, with the error about "Attempt to reset display driver and recover from timeout has failed"

I have updated the graphics card, but still get the BSOD.

So what is the problem?

I have a i3 540 processor, ASRock P55/USB3 motherboard.