Upon hitting the power button, the green light flashes on, the fan attached to the motherboard begins to spin, and just like that, it turns off.
Actually, I don’t think it’s ever really “on” – seems like a small supply of power is hitting the motherboard for a split second, at which point the light flickers on the front of the PC and the fan kicks in, before remaining in its dormant state.
Could this be the motherboard itself?
This is an old work PC that I’m trying to revive.
I had installed XP on it (from ME) and for a few days it worked just great before this happened.
Could be a variety of things but as the other poster suggested it sounds to me like a bad power supply. Normally a pc tech will take everything apart first. Remove the external drives, memory etc and then power on. If it gets further along the POST (power on self test) you start adding components back in one at a time until you find the one causing your problem. But in this case I’d suggest trying another power supply first. Failing that I’d assume it to be either the main board or memory.
Is there a fancy way of checking the how good the power supply is? I replaced the current PC power supply with one from an even older PC (one which we were once told had a bad motherboard (by some tech guy).
As that didn’t work, I suppose it’s possible that neither power supply is good, but how would I know for sure? I’m not going to play around with the good/running PC’s to find out!
I had a similar problem once and it was due to high temperatures. The heatsink (the big cube of metal with a fan on it which sits atop the processor) wasn’t correctly seated and the processor was overheating immediately.
That said, if you haven’t been mucking around with the heatsink yet, it’s probably not the problem. I’d advise against taking it apart to check it without reading up on it first. Otherwise you could make it worse and it can be complicated to put right.
Another temperature related issue to check is to make sure the heatsink fan is spinning. If the fan is broken it could be overheating.
Write down the model number and Google for its manual. Look up how much current it delivers on each “rail”. This will be written “12V: 15A” and means you’re getting 15 amps on the 12 volt rail. Make sure that this is adequate for your CPU and RAM. This website will help you select a power supply that delivers enough power to be useful.
If the power supply is rated for the right amount of power, then make sure it can run under no load. Remove it from the computer and use a paperclip to (carefully!!) ground the pin with the green wire to any of the pins with black wires. To be safe, wear a work glove on the hand you hold the paperclip with. If you don’t understand what I mean by this step, don’t try it! If the power supply spins up and stays up under no load, then one of your computer parts is drawing too much power.
These two steps will ensure that (1) your power supply can theoretically handle what you’re throwing at it, and (2) that the power supply is at least working to some basic spec. What this will not check is whether your power supply is (3) functioning but delivering too little power; however, if your machine passes both of the above tests, that’s the conclusion I would draw.
Just out of curiosity, would you mind posting your PSU make and model, as well as the system you’re trying to power?