MacPro suddenly losing power - what log file(s) can I check?

Question

I've been having a strange problem over the last several months where my MacPro will suddenly turn itself off. It's exactly like a power failure, but only the computer is affected (monitor, other devices all fine).
I bought a UPS thinking that it was a line problem, but the machine still turns itself off once in a while, anywhere from once or twice a month to three times a week.
I suspect it's being caused by something connected to the computer, but there's not too much there - a USB hub, printer, iPhone, a couple of iPods, and a gaming headset.
What log files on the Mac can I check for possible causes to this problem? I tried looking through the Console Messages app for log errors, but there's so much there I was overwhelmed by data.
Can anyone suggest a specific log or two to inspect, or any troubleshooting techniques that may identify the problem? Anyone ever have a similar problem?
Thanks!
-Joe

Answer 1

This isn’t too helpful, but I’ve been having exactly the same problem over the last couple of weeks. It doesn’t seem to be power line (printer and other stuff on the same line don’t go down). Oddly, it turns itself off and then reboots (though I do NOT have reboot after power failure checked).
Two things I’m presently focusing on are (a) the fact that, at least the last few days when I’ve been logging the problem, it ALWAYS does this about 8:15 a.m. Doesn’t matter whether I’m at the computer using it or not. (b) Always, always, always when it’s happened I’ve had Microsoft Word open. But I almost always have Word open, though I’m going to make sure that I don’t have it open at 8:15 tomorrow morning.
Reset PRAM, checked the disk with AlSoft’s Disk Warrior, and downloaded and am currenty running Symantec’s AntiVirus. Can’t think of any likely viruses that would do this, but it seems worthwhile to me to check. I’m going to check fonts for badness of some one or more, and I’m this moment downloading an update to Microsoft Office that is supposed to make it more stable. But an application shouldn’t be able to force a power-down and reboot.
I’m going to the Apple store tomorrow to ask for advice there. My one post here hasn’t gotten any suggestions.
It’s not an obvious kernel panic (i.e., not the usual kernel panic message). Just a little power click, black screen, and a few seconds later a reboot.
-Lofty