i actually have the exact same problem -_-
my pc:
win 8 64 bit pro
i7 3770k
16gb ram
gigabyte z77x d3h
1tb samsung hdd
and the xfx 6950 2gb gpu
if i start the best game ever (battlefield bad company 2 =) with my new os (win8) i can play around 1h and than i recieve an untitled RED SCREEN...