PC wont boot :(

Hi,
my cousin recently built a new system (Athlon X2 4200+, 2Gb Corsair Value RAM, XFX Gefore 6800GS,40Gb HD (IDE) and other HD (Can't remember capacity), Sony DRU810A, Sony DVD Drive) and it's been running fine until last night when he left it for about 30mins and came back and it was off, when he presses the power button - nothing. Any ideas?

Tried so far:
Joining the pins together with a screwdriver to try and boot system
Button in other PC, and it boots

edit: awy to try with just the base components + CD Drive

What happens when the powersupply is first turned on at the back? Do you hear anything or see any led's pulse briefly?

Have you tried a lamp in the same socket that you usually plug the computer into? (Ie, have you tripped a fuse maybe?)

cheers, i'll go give my cousin a call an tell him to try :)

update: tried and tried, nae joy

Tried another mains lead? Fuse may have gone (Unlikely, but possible!)

Do you have another PSU you can try on it? Maybe from an old system?

You didnt mention what make and wattage PSU he has? (Please dont say QTEK or 230W!)

Nah, its a Hiper of some sort, 450/500w I think.

Why do i get a feeling, it may be a cmos problem?

i may be wrong lol...........................

What happened when you tried booting with just the core componenets? Motherboard shorting ?

Nae sure ross, aint spoken to him yet - he's out tonight.

He's getting a shot of another power supply that he'll try tomorrow, ill suggest a CMOS Reset next time I speak to him.

Cheers guys :)