Short description of problem: in two games so far (skyrim and sim city 5) my screen will go black (monitor lit turns orange), music keeps playing, after some seconds music dies and a full freeze happens. In Sim City it only happens in region view, not when looking at the city itself. Skyrim it's random.
I tried everything driver-wise, underclocking video cards, reinstalling things, flashing BIOS, etc that I don't believe it's a software issue. I first believed it was an issue with Skyrim, but now the second game popped up where I have it, I can't believe it is game related either.
As for hardware I installed a new PSU, got one of my ATI RADEON 6870 out (the one I normally use) and tried the other one alone, to no avail.
Does anyone know what could cause these freezes so I can maybe try replacing a hardware piece and test without buying a whole new computer? All games run fine except those two, but I seem to be experiencing the problem alone, those games demand something of the hardware at certain times that makes the thing unstable? I dunno.
It's the weirdest problem I've had with computers so far, and it's frustrating me. Any help at all is greatly appreciated.
Windows 7 64 bit
Pentium i5 750
8 gig ram
2 x crossfired HIS Radeon 6870
EDIT: Monitored the last seconds when the crash happened: