PC powers up for a few seconds / minutes, but doesn't boot

I suspect I already know what my problem is - but can anyone advise me
on how to prove it?

I often have to boot my PC up two or three times for it to boot
properly. Usually, the red "hard disk" light comes on and stays on at
boot up, and nothing else happens. I reboot once or twice, and it's as
good as gold.

Yesterday, the PC wouldn't boot. The monitor just remains blank. No
ram counting, no "press delete to enter bios", no beeps, nothing. The
fans come on, including the CPU fan and after a few seconds, it
switches off. I switch it back on, and after a few minutes, it
switches off. Still nothing. I've removed every peripheral going,
taken out the ram (one chip at a time), removed and replaced the CPU
(P4 2.. The CR2-32 battery is less than 12 months old - I replaced
it last year suspecting it might be responsible for my boot-up
problems.

The motherboard is a Gigabyte GA-8IPE1000; so it's about three years
old. I suspect it's lost the bios somehow. Can anyone offer any
suggestions?

TIA;


Tim

Thanks Paul - yesterday, it wasn't booting at all. I never got as far
as the Bios screen - that's what makes me wonder if the BIOS is
responsible. I know that it's incredibly rare; and you're probably a
lot closer with your thought re the power supply; I'll give that a go
when I get home this evening - I've got a couple of spares laying
around - and see what happens.

Thanks again;

Tim