Please help

[MsMimi]

When I turn on the power the fans (3 of them) begin to spin seconds after turning on and spin for about 4-5 seconds and then stop. I switched to a bigger power supply. No help. I reapplied heatsink goop---no help. I removed the ram, same reaction. 

Can someone please advise what I might do next.

This is a Compaq Presario 6000
Thank you for ANY help.

[Tcasey0478]

So the computer is running without the fans on?

[MsMimi]

No, sorry, I should have said.  The computer appears to be completely dead when the fans stop turning and it continues to do this every time I try to start it.  Just the fans respond (after a few seconds), and then after a few seconds of turning, they also stop.  Then, nothing.

[patio]

Was this PSU new or used ? ?
What make and wattage is it ? ?

If it was less than 30 bucks it may be dead on arrival.

What caused the condition to re-apply new thermal compound ? ? Is this a new processor ?

[MsMimi]

The power supply was original 200 w and it was doing the same thing.  I purchased a new one $42.00 and it is 400 w. It didn't make any differences in what happened. 

The computer was very dirty and I thought the heatsink compound might be degraded, so I cleaned everything and applied the new compound.

That didn't help either.  Thanks for your help!