3pin vs 4pin cpu heatsink/fan connection
i just bought a new mb/cpu and was going to use my old heatsink/fan with it. the mb is an ecs a770m-a, cpu is amd x2 4800+ am2 and the heatsink/fan is the artic cooling freezer 64 pro 92mm that was used with a socket 939 opteron. the freezer pro is supposed to be compatible with am2 boards also but the new board has a 4pin cpu connector on the mb. the heatsink has a 3pin connector. will it still work?
Yeah hi. I bought this AM2 mb with Phenom. The mb came with a four pin socket for the fan, and the fan on the cpu came with a four pin plug, but I had a 3 pin plug copper fan that I preferred the idea. Heat pipes and stuff, you know. I opted for the three pin as my mb manual said this was okay. Cool and quiet works okay, runs between 37c and 42c. No problems yet. You can read the fan speeds in windows vista. Seems all right to me. I'm yet to find out what the fourth pin is for but my system's running okay so, what the heck!
Big bad Dom. I
PWM refers to Pulse Width Modulation which is a method of using electrical pulses to control fan speed and reduce signal noise or interference. It replaces the need for a rheostat to control fan speed.
The fourth pin/wire is used by the motherboard to control the speed of the cpu heatsink fan. Normally a 4 pin fan power cable is plugged into the 4 pin cpu fan header on the motherboard.
When using a heatsink fan with a 3 pin power connector with a 4 pin fan header on the motherboard, the fan will always be on because there is no fan control. The fan will run at full speed.
When using a heatsink fan with a 4 pin power connector with a 3 pin header on the motherboard, the fourth pin with the blue colored wire is not connected. The fan will run at full speed.
There has been an update to the original PWM specification developed by Intel back in 2003. The update allows PWM and fan control with a 3 pin connection. In some modern motherboards there may even be a BIOS setting which allows switching back and forth between 3 pin and 4 pin fan control.