System Shuts Down When CPU Power Connected?

[Oliver_James09]

Hello,

Im completely confused by this problem....

A few weeks back I was using my computer as normal, went out for a bit and came back to a blank screen.
The system fans were still running and other components such as the HDD & CD-Rom drive still had power,
But nothing would happen on the screen, Completely black.

So I restarted the PC, and nothing.... It doesnt even run in BIOS or any visual Screen.
When you press the power button, nothing happens...
Ive tried disconecting all the devices and try & ive tried a new PSU and still nothing

However.... If I disconect the 4 Pin Power connector to the CPU and press the power button..
The fans start up .... If i then connect the power to the CPU, It turns off

I think its a problem with the CPU as it seems to trip the power...
Or is it the motherboard, Im not sure

Can anybody help ?

 

[theAnimal]

You shouldn't connect or disconnect anything on the mobo while the system is on or even plugged in.

If a different PSU didn't correct the problem, then that means it's the mobo or CPU and the only way to find out which would be to try a different CPU in the mobo or vice versa.

 

[Mondoman]

Probably a PSU issue, as noted above.

 

[roadrunner197069]

Definately a PSU issue.

 

[Oliver_James09]

Yeah but ive tried two PSU's , One new one out of another computer that was fine.
But the same thing happens

..

 

[Mondoman]

Well, the next most likely culprit is the MB. CPUs almost never fail, unless they've been overclocked or otherwise abused.

 

[Q9550_@_3730Mhz]

I have the same problem with the my old Opteron 170 PC being unstable. I ended up replacing the PSU and it fixed the problem...