Advice on replace a part or recommend a new rig?

[galadial]

After a bit of detective work I've isolated a problem in my motherboard or CPU. Basically the computer won't boot as the power cuts out after about 1 sec after power on! If I remove the power lead to the motherboard the PSU is fine - hence teh diagnosis. I can't easily diagnose if it's a cpu problem or a mobo problem.

So, I can either buy a new CPU/mobo combination and fit it all together - recommendations please -

Or, buy a bare bones/new PC - again recommendations.

Cheers

Pete