Bob,
I've had similar things happen to what you've discribed for two reasons:
1) Voltage dips. This can trigger the PSU and/or MB to trip the reset. This can even happen through surge protectors.
2) HD problems. One HD I had started causing crashes due to corrupt data it needed to recover. This does seem to fix itself, but I got a second HD and mirrored the dodgey one just in case.
If you still suspect PSU problems there are commercially available testers that simulate the various connections. They're not expensive. It might be a good idea to test it anyway. It's easier to use a tester than manually bridging the contacts on the MB connector and it tests the other connectors (HD, CD/DVD. CPU Fan, etc...)
I've had similar things happen to what you've discribed for two reasons:
1) Voltage dips. This can trigger the PSU and/or MB to trip the reset. This can even happen through surge protectors.
2) HD problems. One HD I had started causing crashes due to corrupt data it needed to recover. This does seem to fix itself, but I got a second HD and mirrored the dodgey one just in case.
If you still suspect PSU problems there are commercially available testers that simulate the various connections. They're not expensive. It might be a good idea to test it anyway. It's easier to use a tester than manually bridging the contacts on the MB connector and it tests the other connectors (HD, CD/DVD. CPU Fan, etc...)