As I completely forgot to mention in a previous blog post, I retasked Bob's old desktop PC into my server, as my old server was getting a bit flaky due to a damaged DIMM slot.
The new hardware worked quite well, except that, very rarely, I'd come to find that the system had mysteriously rebooted. There was never any crash log or any instability leading up to the reboot, it'd just suddenly, every few weeks, reboot itself.
Then, this afternoon during a particularly strong gust of wind, the power flickered and my server rebooted again, and finally the lightbulb went on. I trudged my way downstairs to inspect the matter first-hand, and was at first a bit stymied as the UPS, which had been my first guess as to the culprit, was not showing any signs of distress from either overload nor from worn batteries.
None the less, when I pulled the plug and the UPS cut over to battery power, my server instantly powered down and started spasming as it attempted to power back up again. During this time, the overload warning on the UPS remained silent, indicating that it was still well within its design load.
With this new information, I was able to narrow it down to the power supply inside the server itself. When I upgraded the system, I had only moved the old drives over along with one of the ethernet cards; I hadn't bothered to swap out the power supply as it seemed to be a perfectly serviceable 500w unit, and the one in the old server was only 550w, though it was a high quality aftermarket unit.
Since I still had the power supply from the old server, I swapped it in. I powered up the system (worked first time!) and pulled the plug on the UPS and... nothing! It just kept chugging right along as if nothing had happened.
I am looking forward to not having any more random reboot troubles from my server.