Question : CPU fan only has 3 pins, but motherboard has 4 pin connector Socket AM2

I had to replace my motherboard with an ASUS M3N78-VM Socket AM2.  The problem is that the CPU fan only has 3 pins and the motherboard cpu connector is 4.  I can connect the fan but it runs at full speed, so I assume the 4th pin on the motherboard is to control the speed of the fan by monitoring the cpu temp.  Do I need to purchase a different fan or is there an adapter to make it work?  Because it runs at full speed all the time, it makes the case fairly noisy.  What do I need to do?

Answer : CPU fan only has 3 pins, but motherboard has 4 pin connector Socket AM2

You're right that pin 4 is for smart fan control, so a 3 pin will always run at full speed, unless the motherboard will support votage reduction.

Buy a 4 pin fan, or learn to like white noise.