I'm certain it's not ubuntu's fault, but my desktop is going crazy.
It happens every now and again, for no reason i understand, the computer will just turn off, and then try to reboot itself until i see it - and stop it.
It's not shutting down cleanly or anything, just seems to go off (have never actually see this part); i usually catch it when i get home or wake up and the power light is going on and off, and i can hear fan start and stop fairly quickly.
When it tries to reboot it never even makes it to the gfx card id portion (even before bios) before it shuts down again.

I am just wondering what kind of troubleshooting you can do for this. I don't have spare parts to throw in to do trail and error (plus the problem doesnt always show itself)

first i thought maybe was the psu, but its not that (replaced with 750 watt highclass unit)- so now down to gfx card, mobo and ram ; i guess but i dont think its the ram either.

Anybody have a suggestion?

ps - turning off the psu and turning it back on fixes the problem.