Voltage control with 4 pin fan

modmasta1

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Dec 20, 2017
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I plan to get 2 4 pin fans. They will be connected to my mobo using a splitter cable. I know that I will be able to control them through bios or third party software because they are 4 pin, and since they are connected by a splitter to the same slot in my mobo they will be the same speed.

I want one of them to be slower than the other however. I have voltage step down adapters meant for a 3 pin fan. I am wondering if I can use one of those voltage step down adapters to make one of the fans always be slower.

So the big question here is, does controlling the voltage work with 4 pin fans like it does with 3 pin fans?
 
Solution
You'd select the pwm mode in BIOS for controlling the fans, so I'm not sure if the adapter will work in this case. It would reduce the voltage, therefore the speed, but I'm not sure if you'll be able to control the fan speed. It will have a constant speed.
You'd select the pwm mode in BIOS for controlling the fans, so I'm not sure if the adapter will work in this case. It would reduce the voltage, therefore the speed, but I'm not sure if you'll be able to control the fan speed. It will have a constant speed.
 
Solution
4 pin fan speed is controlled by PWM (pulse width modulation). Essentially, this turns the fan on and off rapidly to change the rpm of the fan. In contrast, 3 pin fans are voltage controlled, i.e. the voltage is reduced or increase to set the fan speed. Your mobo will work with either 3 pin or 4 pin fans. So, if you want to always keep one fan a little slower than the other (off of the same mobo header), get 3 pins fans and use the voltage stepdown adapter on one of the fans.