Fan Pins

[PleaseHelpIdk]

So I'm attempting to build my first PC with the guidance of my own knowledge and research of pcs and now I have came to a blockade. So I was looking at cases with some pre-installed fans to save money on individuals fans, and I noticed that it only specified the fan size, 120 or 140, but never the pins. I know that the fans can come in a 3 pin or a 4 pin factor but after looking through the internet for some time, I couldn't come to a conclusion. My only idea of how this works is that a 120mm fan has a 3 pin socket and a 140mm fan has a 4 pin socket. To my extent, I know that the extra pin for a 4 pin fan is used to control the fan speed, so does that mean if the fans come in a pre-installed form, does that mean the included fans are a 4 pin? 

[Simon771]

It's not true taht 120mm fans are 3 pin only.

4th pin is for PWM or Pulse-width modulation. It's used to control your fan speed.

 

So if preinstalled fans are 3pin, you won't be able to lower RPM with PWM.

[PCGeek]

There is no correlation between fan size and pins.  Generally 4-pin fan headers are PWM which stand for pulse width modulation and is a special method used to deliver variable power to the fan motor.  You will find them more commonly used with CPU fans.  While you can get PWM fans for case fans, you will find 3-pin fans commonly supplied with cases.  You can plug the 3 pin fan into the 4-pin header as long as you line up the notch that is on the header.  You can still control fan speed on 3-pin fans as you can PWM fans but the only difference is how power is delivered.  You should be fine with your 3-pin fans and later down the road you want to upgrade to 4-pin fans you can do that.

 

[Guest]

I've got (cheap) after market "silent" 120x120mm fans, which use a MOLEX connector. So only 2 wires. If I would remove the MOLEX, and if I would install an hardware fan controler, I can adjust the voltage, regulating how fast they are spinning. Due to no 3rd wire, I can however not know how fast they are spinning. (making it hard for software based fan controlers, to controll fan speeds)

[slightlyjaded]

The fan size is supported by the case (It's a physical thing after all ) The type of fan is either supported by the motherboard, or in a few cases a fan controller. # pin fans are voltage regulated fans, they are speed controllable, but tend not to spin as low as the next type.

4 pin fans are PWM controlled, as previous posts have discussed these fans because of the fine control enabled can spin slower still than voltage regulated. please note, you can plug a 3 pin fan into a 4 pin conector, they just default to 3 pin fan configs.

[LogicalDrm]

Most case fans included are 3pins. That doesn't mean you can't control them. That part depends on your mobo, or if case has built-in controller or not. All fans can be controlled, even ones without rpm (3th pin) sensor. With 3pins controlling is done with supplied voltage instead of pulses like with PWM. This means few major things. 1) Voltage control needs to be supported by mobo. Most modern ones have it. 2) Lowest possible speed is higher than what PWMs can do, most of the time 30-40%. 3) Speed can be jumpy because of way mobo delivers voltage.