Can I plug a 4 pin fan to a 3 pin header?
If I were to use a Rosewill Model RCW-FPS-401 12" PWM Splitter to split a 4 pin header in my motheboard to three 3 pin headers, would I still be able to take advantage of Pulse-width modulation?
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Apparently a 3-pin fan can plug directly into a 4-pin socket.
Two of the pins provide power to the fan, the 3rd provides an RPM pulse to the motherboard to read the speed. The 4th pin is for PWM speed control.
This link provides some detail: http://www.tomshardware.com/forum/340825-28-case-fans-4pin-3pin-molex
In the case of a 3-pin fan. Speed is controlled by changing the fan voltage. If you plug a 4 pin fan into a 3 pin socket, the fan speed will be controlled by voltage and it'll still work. The plugs are keyed so you can't get the pins around the wrong way.