I am replacing my cpu fan. It has a 3 pin connector and I bought a new cpu fan with a 4 pin connector. The instruction manual shows that the 4 pin should work in the 3 pin on the mother board. AFter installation, it start and I can see the light inside the fan lights up and the fan spin a bit but then it stop spinning and the system shut down saying the cpu fan fail. I suspect the 4 pin connector is the problem. Anyway to work around that or just the fan problem.
Thank you for your help. The new 4 pin fan should work with the older 3 pin connector on the mother board. Hairystuff is correct, the 4th pin is for the PWM. So I guess the fan is not working and I will return it.