I have a PC that started shutting down (just a cold loss of power) at the windows loading screen. the computer would boot up in "safe mode with networking" but not in "safe mode". I get no error messages, see no blue screen moments before power failure, nothing. I have tried running a OS repair by booting from a XP CD and using the repair console(i guess that might be better called the disk check, dskchk /r), repairing the OS by booting from the XP CD and choosing to repair the windows installation instead of overwriting the existing install. when i tried to repair it the second time the system again drops power at one point in the repair. after that happened a few times i just formated the hard drive and reinstalled clean, or i tried too. In the middle of the reinstall right after i enter the owner name, aria code, and windows product key, power failure again. I have tried replacing the power supply with a known good PS, removing the PCI-E video and running on the on-board(which was never used just in favor of the PCI-E card), removed all other peripherals but the CD drive and hard drive with no change. Even replaced the RAM with still no change. There is no time frame involved in the power failure, it can set at one point for hours with no problem or be logged into "safe mode with networking" and used for long stretches of time with no power loss.
I am going to try using a different hard drive (the thought just hit me when i saw a old one sitting on the table

) though i don't have very high hopes for that solution.
anyone with thoughts on this?? i hope i don't have to trash the MB its only a year+ old