I have my second linux computer, which I keep pretty powerful. It's used as a disk farm and a separate computer for Handbrake processing. All of a sudden the room went quiet, and that computer was totally out.
I assemble the computers in a standard mini ATX case. That allows room for a standard huge power supply. Although I always use surge protectors, I have found that smaller power supplies are flaky. I used to put together small form factor computers, but I gave up. I recently bought a small media computer and put Linux on it. It has been amazingly stable, but I have an expensive power filter on it.
Luckily, it was Cyber Monday, and I found a nice ps on special at ammieland. The old one was 550 W and this one is 850W. The best thing about it is that it is modular. You just put on the cables you need. As well, they are smart enough to include the diagnostic jumper. You just attach that and check that ps zooms up by itself. I wish I had that for the old ps.
Anyway, it worked perfectly. Of all computer problems, this is the easiest. It is best that they just blow out in an obvious manner. I've had lots that go flaky, and then you are doomed, because it looks like anything. Replace the ps first.