My sons PC won't switch on - or it does switch on, but shuts down after a few seconds.

If you take the CPU out it starts up and keeps running - obviously it starts bleeping when it discovers something is missing!

Faulty CPU?

could be, could also be the motherboard.

trouble is you won't know without trying and stiking another cpu might fry it if its the motherboard at fault.

try the cpu in another machine first.

could be psu also. but would say most likely a blown cap on the motherboard... AMD by any chance?

is the CPU fan working?

could be psu also. but would say most likely a blown cap on the motherboard... AMD by any chance?

Athlon 64.

Try bios reset, it may just be pickled or possibly over heating issue if its stayingon for a few seconds

Sounds to me like an over-heating issue.

Make sure fan is working properly and the heatsink is seated firmly and properly on the processor... but if you can try it in another pc or try another cpu in your mobo that would narrow it down!

Try bios reset, it may just be pickled or possibly over heating issue if its stayingon for a few seconds

Done bios reset - no change. Not overheating - problem occurs from cold and all fans running OK. I've cleaned the heatsink of dust.

I'll try the cpu in my own PC - same mobo (AV8).

If the CPU is goosed I can get an OEM one from Ebuyer for under £30.

It may be worth trying the ram as well if you have more there to try, maybe even the psu if it still does after the cpu and ram don't fix it

HTH

Does it crash at the same point every time. If it does it makes it easier to detect what the cause is.

if it works fine with no cpu then i'd say its either the cpu or part of the circuitry that deals with it.

if it was the ram then removing the cpu *probably* would have no effect on it when removing the cpu, unless ofcourse by removing the cpu the POST stops before it gets to the ram :rubchin:

It's very unusual for a CPU to go wrong. I've only seen one ever.

If you can try the CPU in another Pc that would be best and would confirm the problem.

If that works then it's more likely the mobo. But I'd try removing all the bits (pci cards, gfx, memory, hard drives everything). Put it back together bit by bit to see where it stops.

I've certainly seen faulty network cards and graphics cards stop a PC booting in funny places.

It's very unusual for a CPU to go wrong. I've only seen one ever.

I've certainly seen faulty network cards and graphics cards stop a PC booting in funny places.

I'd agree with both those statements, I had a USB 2.0 card once which packed up and wouldn't allow the machine to boot or install windows.

It could be anything really, as aspman says it means tracing back through the system till it works

I'd tend towards a cap on the mobo.

As already suggested try the CPU in another mobo.