So every time you try something it seems to work at first. Is that because it takes slightly longer to either black out or BSOD? Does it BSOD at all? If it does and it reboots instantly you might want to uncheck that option so you can read what Bills' blue has to say.
Try priming your
CPU, if no prob for a few hours try memtest86 and check the memory.
I don't know about the system but you might want to try to check your caps for any anomalies. Or pull out everything you don't really need and see if it helps. Start with one stick of memory, all non OS hard disks, audio if not onboard of course. Well, you know....
