Unexplained non-starter

[KillBoY_UK]

(on behalf of my mate)

Hi all. Turned on my compy an hour ago and got no response onscreen.
"Hmm" says I, and reboot.
This time It gets almost to the Windows loading screen before the monitor loses signal.
I wait a while then shut it down completely. Starting it up again I hear the PSU and Motherboard fans whirring normally for 5 seconds before it turns itself off. This is the best I've been able to get out of it since.

I've tried to narrow it down to either the motherboard or the PSU, stripping it down to the bare bones (Motherboard PSU, CPU and 1 stick of RAM) and it does exactly the same thing.

Any ideas? Any advice or suggestions would be welcome at this point. I've no spare parts to swap round otherwise I'd have done that by now. Help?

btw, I've had this system running fine as is for around 6 months until now.

Specs:

Motherboard - Asrock 939 - Dual Sata 2
PSU - Hiper Type-R 480
CPU - Athlon X2 3800
Graphics card - Radeon X1900 XT
2gb of standard RAM

 

[dr. sarf]

Eeek - Asrock!

Try the usual; clear the CMOS, then access the BIOS and setup the RAM voltages and Timings.
If it POSTs, and loses signal after the Windows Splash screen, try POSTing in safe mode.

 

[KillBoY_UK]

this is me Killboy here ,

Tryed the normal stuff , + removing all cards and just having 1 stick of ram, still has the same effect , it only "half" powers up when you swich the PSU on and off on the back the case power button dose nothing , he came to me with this when i was busy in a wow raid but tonight im going to stick in my Corsair 620w and see if its the same or similer as at this point it could be the PSU or motherboad and i can test the psu but not his motherboard fully

 

[Aod]

it sounds a lot like the PSU has gone to the big faraday cage in the sky.