Recently my computer just shut off by itself, and would not turn back on afterward. All cables have been checked and the surge protector works fine. How do I pinpoint the problem between the cpu-motherboard-powersupply? I don't have backup hardware that I could just plug in a spare and find out. My cpu doesn't look fried, but then again I've never seen what one would look like. I could smell something different when I looked inside my case which seemed to be coming from where my powersupply plugs into my motherboard, but I've never had power issues before. Would a powersupply just instantaneously die? Thanks a lot. :)

When you turn on your computer, does the Power Supply fan works? (in the back of the Power supply)

Nothing happens at all when I turn on the power, not a sound, but my motherboard has a led on it that still lights up while the main power switch is on.

how about other things? is HD LED on? any beep? HD sound? color of monitor LED?

If the psu fan does not operate you have a psu problem. How old is the pc? I would start with the pc unplugged from the mains, open the psu and avoid touching too much. Check its internal fuse or fuses as I suspect one has blown. Clean the psu and its fan with a good blow out with a hairdrier set to cold and maximum blow. Use a long haired brush to assist. Good luck - keep us posted.

There are no other lights (than on the motherboard) that light up, no beeps, nada, when I push the power button. The powersupply is a 250watt unit that I purchased about 4 years ago. When I upgraded my computer over a year ago I didn't think it was necessary to get a new powersupply. Thunderbird 1gig/266 on an Asus A7A266 mobo. What little I know about powersupply problems though is that they usually don't happen so abruptly. I had not experienced the smallest problem up until that point. One other thing, while my main power switch is on and I touch the metal of my computer casing, I can feel an electrical tingle in my fingers. It's kinda kooky. Thanks for all of your help. :)

well with that last statement I would say you were grounding the power supply to the case somehow. Although since this happened suddenly that probably isn't the case. I would recomend you try starting the computer out of the case with just the video card, mobo, memory, and cpu. If that doesn't work then my first instinct would be that you have a bad power supply. Something like blowing a fuse as was suggested above could occur instantaneously.