I have a pc with Pentium 4 on an Abit AL8-v motherboard. Its been running fine for last 3-4 years although it started to hang intermittently recently. Now when I turn on the power at the mains, it starts to boot up with fans etc coming on (even though I have not pressed the on switch on the case). Then it dies after a few seconds. If I leave it there, it may do same after a hr or so o may be not.

The boot sequence goes something like C1, 45, C3, 25, 2A, 26 (or 2b), 98, 99. And thats where it stops.

Unfortunately I cannot find a code 2A in the manual. Code 98 means re-assert atx power supply and 99 is power off.

I have changed psu, no difference. Reseated the cpu heatsink with new paste; no difference. Removed the graphics card, no difference. Removed ram, no difference. Unplugged all sata connections and unimportant power connectors, no difference. I am coming to the conclusion that maybe the motherboard is fried.

Any ideas on this? And why does it start the boot process without the on switch being pressed?