Presario P4 Nightmare

Andy 01

Dec 31, 2010
First post here as it looks a good place !

My old PC, acts as a media server to other devices in the house.
A couple of weeks ago it decided it will not power on !
You get case fan run for a couple of seconds, and then it shuts down again.
It does not appear to complete the POST.

Its an old Compaq Presario S4490UK, with a socket 478 P4, 2.8 processor, and an Asus P4SD-LA mobo.

The last thing I had done to this PC is remove and re-mount the CPU fan as it was noisy. It ran ok for the rest of the day, but would not switch on the following day.

I disconnected everything from the mobo except for the CPU, RAM and fans, and it still failed to POST.
I disconnect the RAM, and you get a warning beep, but it still shuts down a few seconds later.

I exchanged the PSU, no change, so I was left with what I thought was a CPU or Mother Board fault.
I exchanged the Cmos battery to be safe, no change !

I obtained another CPU, and it done the same ! (Yes, installed with correct paste)
I have just installed another Mother Board, and it still does the same !!

What the heck am I missing here ??

Could the mobo be failing to see one of the fans run, and would that shut it down ??
(They do both run !)
The only other thing I can think off is the original fault was the mobo, and that's fried the replacement CPU.

Any other thoughts guys ??


Have a look for bulging capacitors in the area around the CPU. If two or more memory modules, remove one and reboot. If no improvement replace first, remove second module. Try again. Repeat for number of memory modules.

CPU fan may have failed -- most computers won't start if CPU fan is unplugged etc.


Jul 29, 2010

So to clarify, you have changed the PSU, Processor, CMOS battery and motherboard.

A couple more things you could check.

1. If you are running 2 sticks of ram try taking one and try boot, then swap the sticks, if one boots and one does not it points to a memory problem. You could also download a program called memtest, burn it to cd and test your memory (

2. Take your hard drive out and try and get into the bios. If you can get into the bios, check its settings to see if the motherboard can see the RAM and the CPU.