It just rebooted again, another 15 minute interval. No parts are bulging on the power supply. The only thing I can do is check the voltages when it's hot, my theory being that the reboots are heat related, although there is no obstruction to air flow and the air conditioner is running at 72. My friend can solder better than I can so that's not a problem, but if nothing is bulging then what do we replace? The fan could be bad I suppose (it does spin, although kind of slow compared to a PC fan), or maybe the replacement hard drive gets a little hotter and the fan isn't compensating. The hard drive was fully tested and wiped a few months ago and then sat on a shelf until now. The computer it came out of had no problems. I find it hard to believe we replaced one bad drive with another - and that we somehow managed to copy the truncated backup without error and restore it to this other drive. And it's still messed up after kickstart 52 - but another full test and a known good backup from the internet is the last thing I can try in regards to the hard drive. Edit #454566: 11 minutes this time.