BleepingComputer.com: Diagnosis Showed Nothing Wrong

hi

have a puzzling problem and tech guys at Circuit City don't know what to do. its a compaq presario desktop 4 CPU 2.66 GHZ 86.0 Free on hard drive with 1 GB RAM. nothing has been replace in the guts of the computer except for RAM. Never even had a problem with it until now. The computer is 5 yrs. old.

all of a sudden it has started turning on and off but not all the time. both fans are working. i took it to circuit city and they ran they diagnostic test on it which took several hours. told me there was absolutely nothing wrong with it. got home, started doing some work on my computer and it started the same thing again. Circuit City said it never turned on or off for them. I am beginning to think that when I am working or surfing that that is when something happens and it turns on and off. it is not the monitor, and i have replaced the power cords, upon circuit citys suggestion.

any ideas out there or suggestions - i am taking it back to the circuit city techs today but they seem to be clueless also. so thought i would give them some things to check on before i took it back.

thanks for any suggestion you can offer.

Can you try using the computer in another location, eg at a friend's house, to see if it does the same there? That would eliminate something in the environment, eg power connection at your place.

Also, does it go on and off just like someone pressed the soft power button? I had a system that did odd things like that once, there was a blob of hot-melt glue on the back of the on/standby switch that touched the wire terminals. It had become electrically conductive, and the board would sometimes think the button was being pressed. Removing the blob of glue fixed it.

I'm not sure what tests they did on it, But I would make sure all fans are going good, check for excessive dust, Test the power supply and swap power cords and electric sockets, test the case switch and just sort of go from there, quite a few possiblities of why its happening.
Is it giving you a bluescreen before it shuts off? Any certain program you are using when it happens? Does it beep at all when it shuts off or give you anything other than the single short beep when you start up? Error messages?

If that CMOS battery has never been changed...it's overdue, IMO.

Louis

Do you have any problems with any other items plugged into the same receptacle? The contacts on some old receptacles can become worn and may not make good contact. Plug a lamp into the receptacle and move the plug a little and see if the light flickers.