Smart fan and Cool'N'Quiet settings?

[enarchay]

First, what exactly is the difference between Smart Fan and Cool'N'Quiet? Do either of these shut down my system if it gets too hot? If not, what function does that, and where can I find it in BIOS (and what should I set it to)?

Second, what settings should I put Smart Fan at? I wasn't sure. It gives the following options:

Smart fan target - 40c/104f, 45c/113f, 50c/122f, 55c/131f, 60c/140f

CPU minimum fan speed: 0.0, 12.5, 25.0, 37.5, 50.0, 62.5, 75.0, 87.5

Cpu fan PIN select: 3 or 4 PINs.

It said at the time that my system temperature is 43c/111f and my CPU temperature is 31c/86f.

What should I set these settings too and why?

 

[uh_no]

cool and quiet allows the multiplier on the CPU to be lowered when there are idle cycles so that the temp goes down and the fan can slow down

no idea about smartfan