The 3 connector fan is very common use in laptop it can adjust the fan speed according to the cpu.
Cpu cooling fan 3 pin vs 4 pin.
Now 2 pin cooling fans have been less to use because the fan of 2 pin cannot meet the requirements in terms of shifting etc in contrast 3 pin 4 pin fan is the main stream now.
For custom cooling usually the pump is contrlled by the motherboard cpu fan header 4 pin and the radiator fans are controlled either by the case fan 3 pin motherboard headers or by a module eg corsair h100i.
You use 3 pin fans for case fans.
Nb noiseblocker nb eloop b12 3 specs.
A lot of motherboards have one 4 pin header for the cpu and 3 pin headers for any other fans.
Any option can be made to work though.
A four pin connector is a little different than the three pin connector since it has the extra fourth wire used for controlling and sending signals to the fan which likely has a chip on it that tells it to slow down or speed up in addition to the other wires the three pin connector has.
I finally replaced my cpu fan from a 3 pin to a 4 pin connector to hear the difference in sound.
2 advantages to 3 pin vs 4 pin fans 3 pin computer fan.