Strange issue with PSU and PCI-e

[mullen]

Hi,

I recently bought a new case and PSU. After installing everything, my PC seemed to work fine. However, after a day of use it powered off. I had to unplug the power cord and plug it back in before it would turn on. Soon afterwards, it turned off again. It even happened while I was in the BIOS settings.

After swapping things out I found that if I unplugged my PCI-e graphics card, (nVidia 8500GT), the system would power on and stay on. I bought a new graphics card and plugged that in, but after 10 minutes it turned off. I even tried it in the second PCI-e slot on my mobo but had the same problem.

Just when I thought my mobo was on the way out, I tried a friend's PSU. This solved the problem. It's a bit baffling as my PSU is 460W (CoolerMaster), my friend's is 480W (Hiper) and they should both be more than enough for my setup - Core2Duo E6300, 2GB DDR2, two SATA hard drives, a DVD writer and a PCI-e graphics card, although both my old graphics card and the new one I bought don't require dedicated power from the PSU.

Has anyone come across anything similar before? I don't know enough about PSUs to fathom it out.

Cheers,
Dan

 

[mullen]

I checked and they're all just over those values, definitely within 5%. According to both of the graphics cards' specs, they should each only require a 300W PSU. It's odd that the faulty PSU only cuts the power when a PCI-e card is plugged in.

Ah well, I'll have to return the PSU. Trouble was it was part of a case+PSU bundle and they want the whole thing back - what a hassle!