Computer wont turn on without pulling PSU

[bvdave]

so im not sure if its the motherboard, or the PSU, but my wifes computer has been refusing to turn on the last few days. the only way ive found to get it back on is to unplug the power supply cable (24pin one) from the motherboard and plug it back into the board again. then it will power back up, but if she leaves it (and and always does) alone and it goes to sleep, it powers off, and will require another yank of the power cord out of the motherboard to get it back on again.

any ideas what could cause this? is it the PSU? motherboard? im at a loss

she has a AMD 3 core cpu, AM3+ Mainboard, 650Watt PSU, 8gb ram, 6970 video card and nothing has really changed in her setup in a while save getting a new monitor about 2 months ago.

any help would be greatley appreciated

 

[JamesSneed]

This is a symptom of a PSU starting to fail.

You may try pulling the BIOS battery, obviously with the power disconnected. This can on occasion fix an odd issue like this. When you do this you should see that the system time in Windows has reset.

 

[bvdave]

ive pulled the battery, but.. I dont think I did with the power unplugged (well it was unplugged from the wall at the time but not the motherboard) ill give it another shot today and see if I have any more luck

 

[jaquith]

A clear sign of a failing capacitor(s) is to unplug, fully discharge, and 'magically' get it working. I'd replace or RMA your wife's PSU.

/edit - If buying new then look at either Corsair or SeaSonic.

Example $89 (15% off) SeaSonic M12II 650 SS-650AM 650W (Bronze) - http://www.newegg.com/Product/Product.aspx?Item=N82E16817151106