[Cromcruaich]

Tough one that. I presume it used to work?

In that situation I normally strip it down to the bare minimum - unplug all hard disks and cables, take out all cards cept the graphics card (use onboard if u have it), unplug all peripheral fans (just have the cpu and chipset ones going), use only one known good stick of ram and see if it posts.

Check that the cpu fan is spinning up (many motherboards wont post if they detect or think that the cpu fan is knackered).

If it doesnt - try a different stick of ram and a different graphics card. If it still doesnt work its either the cpu, the motherboard or the powersupply.

So powersupply is the next easiest thing to test - you can get tester units for about £7 - or if you have a spare try that.

Still doesnt work - your left with cpu or mobo. Take both out and do a very close visual and sniff check looking for leaking capacitors and scorching. This may immediately give you a clue as to which one is knackered.

If still no luck you are in the realm of using spare mobos and processors to find the culprit.

Good luck!

Oh, from experience sudden inability to post if ive not changed anything or otherwise been mucking around in the case in a previously working system has been down to a power supply gone bad.