Fans & fan connector question

[Dawelio]

Hey guys,

So I've been looking at 3 fans and don't really know which one to get... for radiator use and as a front intake fan.

Silverstone AP121
Noctua NF-F12 PPC 2000PWM
Phobya NB-eLoop (Black)

Which one would you recommend is the best, for both rad use, intake fan and as being controlled through something like Corsair Link or other software?...

From what I understand the Noctua has a 4 pin connector, but what does it really do?... as I've seen the molex to 5/7/12v adapter having 3 pin connector, although one pin is missing.
Same on my motherboard fan headers... now, what I don't get is what this "PWM" is for really?... is it the 4th pin that makes it able to be controll the speed of the fan etc?...
And what is the really big difference between a 3 pin and a 4 pin?... as noctua's has 4 pin and Silverstone's uses 3 pin one.

I must be really dumb as I don't get the explanation of Google, so thought you guys could perhaps do a explanation in basic english for me?... as I'm Swedish

Thanks!

 

[Wraith]

PWM (Pulse width modulation) is just a more energy efficient way to run fans (motors), in which the voltage (current) is switched on and off really quickly rather than having them on constantly.

When you talk of 3 or 4 pin headers, they are as follows.

3 Pin: 1 voltage in, 1 voltage out, 1 speed monitor
4 Pin: 1 voltage in, 1 voltage out, 1 speed monitor, 1 PWM switch.

3 pin fans require speed reducers to control their speed, hence the need for a 5/7/12v adapters or a separate fan controller, 4 pin (PWM) fans can be controlled directly via motherboard headers.