Can a bad power supply cause the computer to start up when plugged in to the wall?

farmerdudley, I'd have to say no. A power supply is just a transformer. When they go bad, they usually stop putting out power or put out the wrong power causing crazy things. A machine starting on it's own as soon as it's plugged in sounds more like a shorted on/off switch to me. Prove/disprove that by plugging it into something like a switchable power strip, extension cord, switchable wall plug, etc. HTH. Ed in Texas.

Is that what's happening? You unplug it then plug it back in (for whatever reason), and it powers up? Or, is it powering up from a powered down state while the power cord is plugged into the outlet? "So won’t you give this man his wings What a shame To have to beg you to see We’re not all the same What a shame" - Shinedown

PC COMES ON AFTER A POWER LOSS RESUMES: (or starts when plugged in) Restart computer into BIOS, go to Advanced in the Menu Bar, select Power On Options in that list, select "After Power Loss", change ON to OFF, move to File in the Menu Bar, select "Save changes and Exit" Your BIOS may be slightly different, but you get the idea. Mine is a Compaq Presario, and did that.

When I plug the computer into the wall outlet, the computer starts up. All of the fans are working, but the computer won't boot. I can't get into the bios because the computer won't even display anything so I can edit the bios. I tried swapping out different video cards, but nothing. The hard drive won't crank up either. I'm thinking bad mobo. Any suggestions? I'm really at a loss. Thanks ya'll.

Just some information --- Do you get any Beeps when starting computer ??? http://www.sysopt.com/tutorials/art... BIOS Error Beeps, Messages, and Codes Check to see that Case and/or CPU fans are running. http://www.howstuffworks.com/power-... How PC Power Supplies Work A yellow,or orange, monitor indicator light indicates no signal is getting to the monitor from the video card. Could be the card is not sending a signal, or problem with the cable or connectors. Card may not be seated properly. You need a green light.