Homebuilt PC now not booting

[Spiny Norman]

Guys - I'm hoping someone can help me troubleshoot my son's desktop. It was self built in 2009 with the following spec. I got the original spec from this site so I thought it would a good place to get help. If this is in the wrong category please let me know:

Case: Cooler Master Centurion 5
Motherboard: NVidia Geforce 6100 Micro ATX AMD Motherboard
Video Card: Sapphire Radeon HD 4850 512MB PCIe
Power Supply: 400CX 400W Corsair
Processor: AMD Phenom 8650 2.3Ghz
RAM: G.Skill 4GB (2x2GB)
Hard Drive: Western WD640 SATA
OS: Windows XP

It's just stopped working. After pressing the 'on' switch, the computer lights up, whirrs a bit, the CD light flashes, the monitor starts up, the lights on the keyboard flash but after a few seconds it just dies.

Can anyone help me start to figure this out?

Many thanks

 

[ur6beersaway]

Most of the time on & off is a shorted motherboard (back) to the case or a pinched cable.

 

[Stevemeister]

You are not having much luck - it could be the motherboard again. I've had new from the box MB's that are DOA and others fail after a few months. I've also had PSU's fail, new hard drives that are duff and RAM that is defective - all of which were bought new. As I think you have discovered there can be a lot of trail and error involved in troubleshooting and its harder to diagnose when the fault may be intermittent but given you have replaced most items I would suspect the MB. The fact that you are getting power to the fans and then a shutdown leads me to think the PSU is okay plus you replaced it not that long ago . . . my experience of PSU issues has been that if it is dead the computer won't start at all.