A few days ago, my PC gave me a shutting down prompt and it turns itself off.

Now, as long as the PC is plugged into the wall, my PC will boot up by itself, starts up for 3 seconds and then shuts itself off. I was unable to start the PC back up manually.

Then after 15 seconds, and it starts booting up by itself for a few seconds and shuts off again. This keeps happening as long as it's plugged in. I unplugged it for a few hours, but as soon as I plugged it back in, it started booting up by itself again and shutting back down continuously.

I replaced the power supply today, but nothing has changed. It is still giving me the same symptoms.

Can anyone help me?

is it overheating?

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For the problem u stated , i think its due to the cooling system, CPU fan may not be working

this causes the system to overheat and caue automatic switchoff

After temp goes low system trying to power up, which again causing heating and switch off

so check ur COOLING SYSTEM

Can you enter into the BIOS?

Off the top of my head I would say your BIOS died or a memory module went bad.

My bet is the BIOS died.

Clear the CMOS (make sure you unplug the power supply or you have a good chance of ruining the BIOS if it is OK), by moving the jumper pin on the motherboard.

Reboot and see if that helps, if not I'd say you lost the BIOS.

first of all THIS is not the way of posting any Qns

READ FORUM RULES

For the problem u stated , i think its due to the cooling system, CPU fan may not be working

this causes the system to overheat and caue automatic switchoff

After temp goes low system trying to power up, which again causing heating and switch off

so check ur COOLING SYSTEM

Very true, check that first. If the fan isn't working or became unplugged from the CPU fan connector on the motherboard that will definitly casue this problem too.

I replaced the power supply today, but nothing has changed. It is still giving me the same symptoms.

LOL! There's nothing better than replacing parts, without knowing what's broken.

Silly question, but have you tried it in a different outlet? Also, if it powers up and down again, I'm quite certain your power supply is fine - this sounds more like thermal protection in the BIOS powering the box off (without warning, as it does). You sure your processor and heat sink are OK?

Overheating in 3 seconds just booting up though?

Capacitors...check the capacitors on the motherboard. Particularly the ones in the immediate area of the CPU. The top of the capacitors should be relatively flat. If they're the least bit "domed" or appear to be leaking then that's your problem. A "thermal shutdown event" is the exact error message that the Dell OptiPlex GX720's give when the capacitors start going on them (as an example). Eventually they get to where the system won't even boot.

What kind of system is this? If it's a custom built what's the motherboard model number? The Intel D865PERL motherboards also had a capacitor problem.

Edited December 10, 200718 yr by nmX.Memnoch

Overheating in 3 seconds just booting up though?

Capacitors...check the capacitors on the motherboard. Particularly the ones in the immediate area of the CPU. The top of the capacitors should be relatively flat. If they're the least bit "domed" or appear to be leaking then that's your problem. A "thermal shutdown event" is the exact error message that the Dell OptiPlex GX720's give when the capacitors start going on them (as an example). Eventually they get to where the system won't even boot.

What kind of system is this? If it's a custom built what's the motherboard model number? The Intel D865PERL motherboards also had a capacitor problem.

If I could vote this post up, I would. I will wager a box of CrackerJack that the caps on your mobo are going or have gone bad. This is a classic symptom.