PC won't start?

[Kenny]

Older PC:

Asus K7M m/b
600MHz Athlon
256 MB RAM
350W PSU
ATI 8MB AGP graphics
Standard CDROM
XP Pro/SP2

Pressing ON button on case front PSU & CPU fans start but nothing else,
doesn't even get to POST beep.
Sometimes powering off and pressing ON button maybe 3 times PC will POST OK
and work normally until it's powered off again.
Have reseated cards, RAM and cables.
Tried different graphics card.
Have reset BIOS to defaults although there was no sign of BIOS corruption
and battery checks OK with multimeter.
Suspect PSU or m/b but don't have spares to swap out, which would be more
likely?

 

[charli b]

Older PC:

Asus K7M m/b
600MHz Athlon
256 MB RAM
350W PSU
ATI 8MB AGP graphics
Standard CDROM
XP Pro/SP2

Pressing ON button on case front PSU & CPU fans start but nothing else,
doesn't even get to POST beep.
Sometimes powering off and pressing ON button maybe 3 times PC will POST
OK
and work normally until it's powered off again.
Have reseated cards, RAM and cables.
Tried different graphics card.
Have reset BIOS to defaults although there was no sign of BIOS corruption
and battery checks OK with multimeter.
Suspect PSU or m/b but don't have spares to swap out, which would be more
likely?

faulty PSU supply

 

[Kenny]

Thanks for the reply, trying to borrow a PSU for test then buy one if it
works.

 

[Dave B.]

In my experience the Power supply would be more likely. But I would look for
blown caps on the motherboard before you run out and buy one.

 

[Kenny]

Got this one fixed more by chance than anything else. Came across an old
128MB PC100 module and thought I'd try it but wasn't hopeful.
You've guessed it, the PC booted perfectly time after time. Put the 256MB
back in and the fault returned! This is god quality Crucial RAM.
I know 128MB isn't enough to run XP comfortably so I'll buy 256MB or perhaps
even 512MB.