Can you use a 3pin fan to 4 pin header adapter to give the fan PWM control?

[darcymccracken]

Hi,

 

I have a meshify c mini case and the case fans included are both 3 pin. My motherboard has 4 pin fan headers, Is it possible to use a 3 pin fan to 4 pin header adapter to allow the fan to have pwm control?

[Mira Yurizaki]

2 minutes ago, darcymccracken said:

Hi,

 

I have a meshify c mini case and the case fans included are both 3 pin. My motherboard has 4 pin fan headers, Is it possible to use a 3 pin fan to 4 pin header adapter to allow the fan to have pwm control?

You can use an adapter to run 3-pin fans in a 4-pin header, but they won't be PWM controlled and they can't be.

[darcymccracken]

Just now, M.Yurizaki said:

but they won't be PWM controlled and they can't be.

Is there any point to PWM?

[TrigrH]

Just now, darcymccracken said:

Is there any point to PWM?

Its best to ask what is PWM first.

Quote

The common cooling fans used in computers use standardized connectors with two to four pins. The first two pins are always used to deliver power to the fan motor, while the rest can be optional, depending on fan design and type:

• Ground – common ground
• Vcc (Power) – nominally a +12 V supply, though it may be variable depending on fan type and desired fan rotation speed
• Sense output from fan – outputs a signal that pulses twice for each rotation of the fan as a pulse train, with the signal frequency proportional to the fan speed
• Control input – a pulse-width modulation (PWM) input signal, which gives the ability to adjust the rotation speed on the fly without changing the input voltage delivered to the cooling fan

The board will just lower the fan voltage to control the speed of 3 - pin fans.

[Mira Yurizaki]

1 minute ago, darcymccracken said:

Is there any point to PWM?

3-pin fans are controlled by adjusting the voltage, which becomes a problem because the motors need a minimum voltage in order to turn. So you're likely not going to get anything less than say 50% out of a 3-pin fan.

 

4-pin fans always run at their operating voltage. The PWM signal just "kicks" the motor periodically. So you have a much wider range of RPMs.

[darcymccracken]

Ah ok