computer won't start up

[jmbels]

When I turn my hp desktop on it only runs for a few seconds and then shuts off for a few seconds then on again and off again. It keeps doing that until I shut it off. Any help would be great.

[ronallandottk]

It's possible your CPU fan has seized up, and not cooling the CPU, or the heatsink fan is so dirty that it doesn't really radiate heat from the CPU. If this is indeed the case, the CPU (assuming it's a Pentium 4 or newer or an Athlon 64 or newer) will automatically shut down when it overheats. It'll resume working when it cools off, and shut itself down again when it overheats again.

Other possibilities may include an overloaded power supply, causing it to cut out when the power drain exceeds a certain level, or maybe even voltage fluctuations from your wall outlet.

On the extreme side, it could also be your motherboard.

You weren't that specific in your description...it shuts down then resumes? It stops midway during the power on self test, than restarts the test? Or does it reboot continuously? If it's the latter, it's also possible your PC is infected with a virus.

If you could give more details, maybe we can positively identify the cause.

[jmbels]

Once I hit the power button the computer turns on, the fan turns on, then everything turns off after a couple seconds, and then back on and off. It keeps doing this until I unplug it, it doesn't stay running long enough to hold the power button. Computer is clean and plugged into the wall. Shut down when I went to bed and started doing this the next morning.

[ronallandottk]

This happened to me briefly not so long ago. In my case, it was solved by simply turning off the power switch located at the power supply itself, on the rear of the computer for a minute or two (not the power button on the front of the PC), just to reset the power supply itself. I'm not sure if this is applicable to you, but if you have a rear power switch, it can't hurt to try.

Do you overclock or something, or change anything in the BIOS? It's also possible you changed a setting, perhaps CPU voltage, or memory read timings, or a FSB or multiplier setting that the machine can't tolerate, hence it won't boot. For some reason, the BIOS settings could also be corrupt. If this is the case, you probably have to reset the BIOS, you can do this by using a jumper on a couple of pins on your motherboard, you have to check your motherboard manual for this, but all motherboards have this capability, so it's not really difficult to do.

Other than this, you may need to inspect the inside of your PC for any disconnected connectors and such, perhaps remove and reinstall the RAM, reseat any expansion cards which may have worked loose.

Check your heatsink fan if it's clean and working properly, as I mentioned earlier, an overheated processor can cause the symptoms your describing.

Do you use a UPS (uninterrupted power supply) or power strip, or surge suppressor? Try plugging the PC directly to the wall outlet itself, your UPS, strip or suppressor may be malfunctioning.

Try plugging into a different wall outlet, for some reason maybe you're having electrical fluctuations.

If all of these don't help, it may be possible your power supply is malfunctioning, it may need replacing.

I hope one of the suggestions here can help you.

[kris]

Good advice. I have also found that dust creates lots of problems, so you may want to shut down and use air to blow out any visable dust, from the mother board, fans, power supplies and such.