Bad power supply? Motherboard? Powers off within 1 to 20 seconds.

[SteveEG]

A formerly working (for almost 3 years) sandy bridge build (running 24x7) now refuses to stay powered on. When I press the power button, the fans spin up, and sometimes it beeps and gives me a bios screen, sometimes even gets to recognizing the hds and has even started to boot a few times, before just powering off.

Any thoughts? I've reseated the ram modules. Confirmed all connections (sata, power, etc) are tight. My best guess is that the power supply is misbehaving. But I'd hate to replace the power supply if you guys think it is likely to be motherboard or cpu issue. Thanks in advance for any ideas.

Steve

 

[bmoag]

The bad news is that its most likely the power supply.
I would regard what you are seeing as meaning the power supply is not sending a "power good" signal to the motherboard. You can look this up for yourself.
The good news is that a decent name brand 650 watt unit is less than$100.

 

[SteveEG]

Thanks for the input. Confirmed. I dropped a new power supply in and all is good. I am even under the 3yr warranty, so can get the bad one replaced to have as a spare!

Thanks.