Hi I have a situation a little more complicated than the title might suggest... I am fixing up an old computer. I noticed under stress the CPU temperature spiked to 85 C almost instantly. I opened up the computer and noticed the CPU fan was not spinning. I tried hooking up a 3 pin non-PWM fan to both fan headers on the mobo and the fan worked for both. The current 4-pin CPU fan however doesn't work on either when the computer boots and BIOS reports fan speed as N/A. I tried plugging the current CPU fan into another 4-pin PWM header on another mobo and it spun up right away. Does this mean the mobo's PWM functionality might be busted? I loaded BIOS defaults and toggled Smart Fan on and off with no results. I actually just found a spare 4-pin PWM fan I forgot about while writing this that I'll hook up later tonight or tomorrow and see what happens. Thanks!