HP Pavilion CPU fan mod

I was given an HP Pavilion by a friend because it wasn't running very well and she decided to get a laptop. When I opened it up I found that the CPU fan was missing, so I ordered an aftermarket CPU heatsink & fan and installed them with Arctic Silver. The problem now is that most of the time I get a "CPU fan fault, press F2 to continue" (or something along those lines) error message on power-up. I'm going to be giving this PC to my mom to replace the ancient PII 266MHz she has now and don't want her to have to deal with this. I've been told that the error is due to the fan speed monitor not getting the correct signal off the yellow wire of the aftermarket fan, and also that there are ways to fix this. I believe the one I read about mentioned using an LED or small resistor to ground the yellow wire to the black wire, but am not 100% sure. Anyone have any ideas? Thanks.

 

To check that it is not just a sensor fault, on startup, press del, or f2 to get into yourr bios.
Look for something like cpu fan detect, and turn to off,go to the shut down temperature , and set this to 55/60, and restart.
See if fan is spinning, go back into bios, and check (system health to see what the cpu temperature is - let it run for a little while-10/15 minutes,- if it keeps reasonably stable, then you are o.k, and it might just be a faulty sensor.
You can download Everest 220,from majorgeeks downloads, or something like speedfan, if you want to keep your eye on temperatures while its running

 

Everest
http://www.majorgeeks.com/download.php?det=4181