Computer powers up and down by itself?

[Vertigo-1]

I have this rather bizarre problem with this E-machine I'm trying to repair. When I try to hit its power button, the computer won't power up. However, if I either unplug and replug in the power cord, or unplug and replug in the power supply cable to the motherboard, the computer will power up just fine. The power button will then work to turn the computer off...but not on. Then occasionally, if I just leave the power cord connected, the computer will turn on by itself...or if it's on, it'll turn off. It's driving me nuts...what could be wrong??? I suspect perhaps a short in the motherboard...maybe I should try some washers underneath the screws holding down the motherboard?

 

[will889]

Check it out under the motherboard. Also your powers upply there could just be bad and giving radically nonsenical voltages. I bet if you got a new PSU (you can get the emachines power supply at directron) and clear cmos, then reset the deafaults, then optimal values you will be ok, and in clearing the CMOS you also need to take out the CMOS battery (or just move the jumper pin over 1 pin for 5 min) and remove the ATX power supply form the board. Then when you move the jumper back to retain rehook up the ATX connector from the PSU to the board, and anything else you undid - hook back up (Im assuming you know the drill (grounding yourself) since you are reparing yourself, and all the other details. It's either your board or the power supply more than likely. Probably the power supply. Those things used to go out like K-mart lights a few years back.

 

[oldman420]

also make sure the power switch lead is firmly connecter and test at the pins with a screwdriver to see if maybe you have a bad power switch

 

[DKlein]

For some reason my computer turns itself on for no good reason sometimes... then it won't for a month... then it does twice a day... then it doesn't...

 

[Vertigo-1]

Originally posted by: oldman420
also make sure the power switch lead is firmly connecter and test at the pins with a screwdriver to see if maybe you have a bad power switch

Could you go into a bit more detail about this? I've never done this before.