Parents computer won't boot - strange behavior

[krtlxx]

Hello!

My parent's computer has recently developed some problem and now fails to boot. It is an HP Pavilion desktop that is about 3 years old. I don't know the exact hardware configuration off hand, but I can get it in a few days if necessary to diagnose the problem. I do know that no hardware has been added/ removed recently. It is running Windows XP Professional.

If the computer is disconnected and then reconnected to a power outlet, the fans turn on max without the power button being pressed. The power light does not come on. Pressing the power button turns off the fans. Pressing the power button again causes the fans to come on max again but the power light blinks rapidly without a steady rate. The hard drive activity light blinks a few times occasionally. The CD drive activity light blinks, with a short pause after every few blinks. It makes a sound like it is searching for a CD. After a while the fans will sometimes decrease in speed. No output is sent to the monitor, and there are no hardware beeps.

I cleaned out the dust a few days ago, and I replaced the mobo battery. No changes in behavior. I was going to try replacing the power supply next. Any ideas? Thank you in advance for any help.

 

[Tedster]

replace your dead PSU and cmos battery

 

[krtlxx]

Thank you for the reply Tedster.

Alright, I replaced the default HP 300W PSU with an Antec 380W earthwatts from newegg but there was no change in the computer's behavior. Did I just get a bad PSU that I need to RMA or is some other part of the computer responsible? I tried disconnecting the DVD drive, hard drive, and all PCI and PCI-E cards to see if they were somehow causing an issue but the computer still will not even POST. I also tried individual RAM sticks.