What do you reckon dodgy power supply ??

[The PIT]

One of my pc's doesn't always boot from cold. I cured for it four days by upping the cpu voltage from a displayed 1.45v and lower to it's present voltage 1.616. In the bios the setting is 1.7v I had to do this to get it too boot this morning.
The proc is a 2.66 gig P4 and once up and running runs 8 - 10 hrs without any problem.

[gangster]

If your bios has the feature to create a delay for starting the pci devices, I'd try it. This once worked for me.

[Wombat]

PCI devices, and/or hard drives. Giving them more time to spin up may let the power drain settle down. But if this problem is accelerating like it sounds, I wouldn't be surprised if you've got a failing cap somewhere, and I'd think motherboard over power supply.

[Brian R.]

I fixed a problem similar to what you're describing by taking the power button connecter that attaches to the MB and crunching it slightly to make a better connection with the pins on the MB. Never gave me any more problem.
YMMV

[The PIT]

Theres a delay of 35's for the hard drives. Booted without a problem today I'll see how it goes.