I have a Dell that's a little over 2 years old. The boot HD failed so I replaced it w/a new HD and reinstalled Windows 7. The system boots and runs w/out any problems. However when I shut the system down it powers off then starts to power back on for 1-2 seconds then powers down. It continues to do this until I unplug the power supply. When I plug the power cord back in it doesn't exhibit this behavior. I've checked all the BIOS settings and reinstalled the OS. I haven't installed anything new except the HD.
Has anyone seen anything like this? Could this be a PS problem? I would hate to think that it's a MoBo problem.
After installing the new HD I originally installed Windows Sever 2008 R2 Server Core (Server Core doesn't install the GUI only a command prompt) It was the first time I'd run server core and I thought I that mybe I had screwed something up so I did a full install of Sever 2008 R2 and still had the problem. Thinking it might be an imcompatibility with R2 I wiped the disk and installed Windows 7 (which is what the system was running when the HD failed) and still had the problem. I've checked OS and BIOS power settings and everything looks OK.
I don't have a spare PSU lying around to test with. I'd have to buy one or pull one out of one of my other systems. My concern with doing this is that Dell used to use different pin-outs on their PSU. I'm concerned that I might fry my mobo.
A different PSU shouldn't be a problem. Modern motherboards are usually 24 pin (some still 20 pin) and modern PSU's usually have a 20+4 pin power adapter to allow compatibility with either 20 or 24 pin.
True some older Dell's did some weird stuff but the Dimension E520 is beyond that era.