Mysterious Rebooting Issue

[mwtb]

Last week, my PC started behaving rather oddly on start-up. I power it on, the drives and fans all spin up, and then it resets before the BIOS splash even shows. It does this for a few minutes before finally starting up and then performs flawlessly.

It seems like something needs to warm up, but I have no idea what. I'm worried that at some point it will refuse to boot at all. The PSU seems the likely culprit, although its a Corsair and only a year or so old. Any clues?

 

[cooljimy84]

Have u tryed returning to the default clocks for the CPU memory etc ?? see if the problems still happen ?

 

[mwtb]

Have u tryed returning to the default clocks for the CPU memory etc ?? see if the problems still happen ?

I'll double-check when I get home, but it's been running at stock for a while AFAIK. I guess I'm just going to have to yank bits of kit until it works, but I was wondering if the symptom clearly pointed to anything.