P4 PC Acting Up

I recently sold my Pentium 4 PC on and its causing the new owner nothing but problems, whereas when here it was rock solid at 3.3Ghz everyday for a year.

Spec:

Pentium 4 2.4c CPU *NOT OVERCLOCKED*
Asus P4P800 Motherboard
512 PC4000 Corsair RAM
128MB XFX GeForce 6600GT
80GB OS/Programs drive
120GB Storage Drive
DVD-Rom
380w Tagan PSU


She rings me up one day - "The PC Rebooted, and is stuck with the error "Overclocking Failed - Press F2 to enter setup" and won't go any further. I go round, enter the BIOS, and its STOCK. I load defaults, exit and save changes - boots.

Its fine for a month then i get a text - "That same thing has come up again" I told her what to do, and its fine for a few hours.

This time, it reboots, and doesnt do anything. The monitor light blinks from orange to blue, then back to orange. So I asked her to leave it alone til I could go and have a look.

Day before yesterday I go to have a look. Thinking it may just need a simple CMOS reset or something. So I:-

held insert at boot - Nothing
Put CMOS jumper in reset position, leave for 2 mins after running power through, then replace - Nothing
Re-seat heatsink/fan and CPU - Nothing

By this point I'm thinking somethings given up, maybe the motherboard? May explain the BIOS getting all "Forgetful?"

Oh I need to go for a second look today, I'm thinking of just stripping the thing right down and re-building as that can usually sort out some boot problems. Also i have a few spare parts (1.8 cpu/fx5200/abit 478 motherboard) so will do some trial and error if the rebuild doesnt work.

Any help apprieciated :)

CMOS battery? PSU?

Everythings fine, yet weird.

I took everything apart, tried diff mobo gfx and cpu and it wouldnt boot.

put it all back together apart from the 6600gt and it booted. replaced the 6600gt and it booted. So all original hardware works....it just never wanted to?

weird.