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Fan control

Wardy98
By Wardy98
in Cooling
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What's the difference between controlling a PWM fan and a DC fan off a 4-pin header?  

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So both types of fan can be controlled based on Cpu temp etc with fan curves? It's just the way that the board controls then that's different?

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So both types of fan can be controlled based on Cpu temp etc with fan curves? It's just the way that the board controls then that's different?

essentially but not all boards are capable of voltage fan control(3 pins) and thats why fan controllers are still popular

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@Wardy98

A pwm fan runs at 12 volts all the time, and the 4th pin on the header switches the fan on and off really fast so you have greater control of the speed. Some 4 pin pwm headers on motherboards don't offer voltage control for 3 pin fans. a 3 pin fans run on voltage control, so to change the speed, the voltage would have to go up and down.

 

Right and wrong. PWM fans don't run 12V all the time. PWM means that they can be started with lower voltages.

 

Mobo 4pin header don't always have PWM. This is case atleast with Gigabytes Z87 and Z97 boards and MSI's Z97 Gaming boards. They do have voltage control always but ways to control it accurately aren't so common. Each mobo maker has own software which can create fan curves and bring somewhat accurate control over 3pins. 3rd party softwares like Speedfan can only use reduced speed, usually the 7V speed.

 

So every motherboard can control 3pin fans. Only some motherboards have all headers PWM enabled. Reason for people using fan controllers is because they allow more accurate voltage based control than mobo and can add more fans (older mobos).

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Huh. Well then thanks for the information then. I guess I just need to do more fiddling in the my BIOS. For the life of me I haven't been able to get any voltage control out of the fans on my motherboard. But it must have a voltage option because if the PWM fans aren't running at 12v all the time, then it HAS to exist. Thanks for the correction :)

 

Your problem might be same as with me. Check on mobo manual how Gigabyte has connected pins. If there's something like VCC, options are full speed or Gigabytes manual/Silent which aren't really doing anything. Reason why I changed from PWM back to 3pin since I can get 3pins to run slower. If they are real PWM headers, your fan could start with like 20% of rpm. (My mobo is Z87X-UD3H)

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