What does the the "System cooling policy" under "Processor power management" on Windows 7 do?

Solution 1:

System Cooling Policy lets you change the cooling mode of your system.

What does this actually do?

Active increases the fan speed before slowing the processor to maintain cooling, while Passive slows down the processor before increasing the fan speed. Passive saves a lot more power as it reduces the clock on your processor, hence giving your more battery time.

Source