I've got an older PC that restarts a few times a day. Took the side cover off and ran it like that for awhile after checking all the fans were working. It still does it. I know this is a PITA to diagnose as it can be software or hardware related. I'm thinking the PSU is crapping out though. Any utilities out there that will monitor the PSU voltage/wattage and write the data to a file? I guess it would have to sample data pretty frequently for me to tell so this is why I ask. Ideally it would sample every hundreth of a second or so for 10 seconds before it starts overwriting the same file. Any other suggestions besides replacing the PSU with another one? If I gotta spend money on it, I'll just buy a new one (PC). Edit: Forgot to mention, hardware hasn't changed in 1-2 years. Also I did a 6 hour long cleaning session removing adware/spyware and some 30 or so programs followed using CCleaner and also revoved invalid registry entries after reboot. Seemed to run fine after that for a few months (no restarts) so I don't think that is the problem? Maybe I should reformat and reinstall XP but I feel like the PSU is the issue and would like to check that first.