Question : Problem: CPU fan dead .. cant access bios

Hello experts,

I have a system that reports that the processor fan is not working and turns itself off after 5 seconds. I installed a new fan which also would not run when plugged into mainboard. I tried two different places.

I then connected fan directly to power source and the fan runs ok. I guess i need to access the bios in order to switch off the fan monitor function but how can i do this ?? If the 5 volt  rail is dead what can i do?

Answer : Problem: CPU fan dead .. cant access bios

It may be possible to use the tachometric signal wire from the fan on the CPU fan header to fool the motherboard into thinking there is a fan running. You would need to pull the +12v and ground from the fan and connect it directly to the PSU as you have now but also connect the Tach signal to the CPU fan connector.  Here is the pinout. Ensure the proper orientation  of the clip  when doing this to get the right wire. http://www.pcdoctor-guide.com/wordpress/images/cpufanpinoutlabeled.jpg