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I have a case fans thats 3-pin if i add a PWM 4-pin extension cable to the 3-pin fans so that I can plug the 4-pin into my motherboard. Would I be able to control the RPM/Speed of the fans if I do it this way? Sorry if its confusing

user1092778
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1 Answers1

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From here https://forums.tomshardware.com/threads/is-there-a-way-to-control-3-pin-fans.2905718/

For 3-pin fans, the connections to it are Ground to Pin #1, +VDC (varying) to Pin #2, and Speed signal on Pin #3. To control fan speed, the mobo header must alter the voltage on Pin #2, ranging form +12 VDC (max) to about +5 VDC. (At voltage less than 5 VDC, the fan may stall and not re-start until the voltage is increased.) This method is called "Voltage Control Mode" or sometimes "DC Mode". The fan speed signal is a series of pulses (2 per revolution) generated inside the motor and sent back on Pin #3 to the mobo for counting and display. Interestingly, this signal is NOT used for actual control of the speed.

4-pin fans work differently. They still use almost the same signals on those first 3 pins, but with one important difference. Pin #2 always has +12 VDC on it, never reduced. Then the new Pin #4 has the PWM signal. Inside the fan a small chip uses that PWM signal to control the flow of current through the motor from the +12 VDC supply, thus manipulating speed. This method is called "PWM Mode".

So the answer is that an adapter would not work because the method of control and signals employed are fundamentally different.

music2myear
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