Damaged CPU?

Hey

I was cleaning out the inside of an old computer today, shocking amount of dirt and dust had built up in and around the fan and heatsink.
I unmounted the processor (P4) and heatsink so I could get all the crap and took out other components to try clear all dust and dirt. But when I reassembled the computer wouldn't turn on.
I checked all connections and made sure I had put the processor and everything else back in right but still no go.
There is a little led on the motherboard where the psu connects to it that lights up when comp is plugged in but when I press button on front of tower nothing happens.

Any idea what it could be? I'm guessing it's not the psu as the board is still getting power but I don't know

 

You sure you put the ram in the correct slots?

Do you get any beeps?

 

Positive everything went back where it came from.

I get no beeps, noises or any kind of action happening at all. I've checked every cable twice. Thought it might have been the power switch cable running from front panel but there's only an audio cable for headphone jack and a USB cable for two USB ports at the front. I figured the powerswitch is connected to motherboard via the USB cable and these all seem fine.

 

Greetings, gouche

Negative - most likely, there will be a twisted-pair cable coming from your power switch which plugs into a header on the motherboard (similar to the illustration below).

I suggest reseating your RAM modules, pulling your CPU again to make sure no pins are bent, and rechecking all connections.

And, a quick question: did the machine work before the cleanup?
.

 

If you have the manual of the motherboard, you can check which connections on the board lead to the power switch. If you pull these, you can check if the power switch itself actually makes a connection between the two wires yes or no. Most probably a very simple problem with a simple solution.

 

Ah yes, you need to put those little cables as pictured above back in, if you cant find the manual, just get the power one and try it in all the ones till it works, it's usually the top left with the top left bar one.

 

http://support.euro.dell.com/support/edocs/systems/dim4550/techov9.jpg

Above is a picture of the system board taken from this site: http://support.euro.dell.com/support/edocs/systems/dim4550/techov.htm#1101565

This is the best picture I could find of the front panel:
http://support.euro.dell.com/support/edocs/systems/dim4550/replac70.jpg

The wide wire on top is for the 2 USB ports, the thin wire in the middle is labelled audio cable and is for the headphone jack while the bottom wire is connected to the actual button I press to turn the computer on. All of these are in place and secured.
I have reseated the CPU and RAM modules but still no go. Am I missing something simple here?
Also the machine worked fine before hand, had just done a clean install of XP and had been running better than it had in a long time.:cry Which admittedly isn't that great given the age of the system!

 

I thought I only needed to apply thermal paste if I detached the CPU from the heatsink? The fan is not actually touching the CPU or heatsink anywhere, it just 'hovers' over them.

 

I think he means the heatsink.

 

Gouche, can't you find any connection wires from the power switch to the mobo?

 

The only wires coming from the front panel are the USB cable and the audio cable.

I'm gonna have a look at getting the front panel off today to see if the connection from the power button is loose or anything. Also gonna try re-seating everything (for the third time!) in case I missed something simple.