3 pin fan to 4 pin connector

deathtaco

Reputable
Nov 22, 2014
66
0
4,630
Hey i want to know if i can use my 3 pin fan on my 4 pin connector on my motherboard will anything bad happen to my motherboard or will i just not be able to control the fan speed?
 
Solution
What mobo? 4 pin fans use what's called PWM, it adjusts the RPM without any voltage increases or decreases. Whereas 3 pin fans use voltage control to turn the fans faster or slower.

You should be able to use 3 pin fans in 4 pin connectors, I have 3 3pin fans in 4 pin connectors on my Z97-A.
What mobo? 4 pin fans use what's called PWM, it adjusts the RPM without any voltage increases or decreases. Whereas 3 pin fans use voltage control to turn the fans faster or slower.

You should be able to use 3 pin fans in 4 pin connectors, I have 3 3pin fans in 4 pin connectors on my Z97-A.
 
Solution
You can definitely plug a 3-pin fan into a 4-pin fan header. The first three pins will be connected (GROUND, +12 VOLT, and TACH). The 4th pin (PWM CONTROL) will not be connected. The "tabs" on the connectors even line up properly so you can't misconnect them.

Typically in this arrangement, the +12V is a fixed voltage, so a 3-pin fan will run wide open (as it would if you connected it to a Molex from the power supply).

For this reason, it makes sense to just buy 4-pin splitters and extensions, since they can be used with either 3-pin or 4-pin fans. If you buy 3-pin stuff, it can't be used with PWM fans.

NOTE: If you have more than one fan (3-pin or 4-pin) connected to a single fan header, you should only have the TACH wire from one fan connected to the header. The computer will "read" the speed from the fan with the TACH wire and there won't be extra signals to screw things up. Most properly made splitters handle this for you by simply removing that 3rd pin on all but one connector. Decide which fan you want to read the speed from and connect that one to the connector with all of the pins.