I did some diagnostics, RAM is good, HDD's are good, PSU is good but whenever it boots up to windows 7 it just shuts off before it can even get away from the welcome screen. I have a miniXP that I tried to load from a USB and right as its about to begin loading XP, all you see is the windows xp logo and it too then shuts off. But when I use Hiren's boot cd or spend any amount of time in BIOS everything is fine. Settings are saving in BIOS so the battery is still good on the MB. Anyway to narrow it down between the CPU and the MB? Aside from switching systems? Anyone have personal thoughts or input regarding this situation? ITs an old AM2 system running an AMD Athlon 6400+ everything on stock. Some GB MB, don't recall the model.