Simple fan-related question

[Alir]

I ordered 2 different type of cougar fans:

http://www.amazon.co.uk/gp/product/B0050TRLK8?psc=1&redirect=true&ref_=oh_aui_detailpage_o03_s01

http://www.amazon.co.uk/gp/product/B0050TRLGW?psc=1&redirect=true&ref_=oh_aui_detailpage_o03_s01

 

One is 120mm the other is 140mm.

 

Both come with a 3 to 4 pin adapter.

 

Only the 140mm comes with a fan speed control cable.

How does the fan speed control cable work? Does it run the fan on minimum RPM?

 

How does the 3 to 4 pin adapter work/where do you insert it into?

 

I'm a newbie, first build, know little about the type of adapters.

 

the 4 pin looks like a molex adapter - dunno what that is either. I was under the impression the 4 pin would just be the 3 pin but with one more pin - not a different adapter entirely.

[Pofi]

Simply put:
No, it lets you adjust the fan speed with software, rather than going just from system default.

sorry, misread the post. yea, it basically reduces the rpm.

[WoodenMarker]

The fan speed control cable reduces the speed of the fan down to 700rpm.

Yes, that's a molex adapter that allows you to attach the fan directly to the psu if you don't have anywhere else to plug the fan. 

[loccilucas]

The actual speed control cable is just a cable with a resistor soldered in line, lowering the voltage to the fan making it soon slower.