Zalman's CNPS10X Extreme fulfills both roles pretty well care of a
cleverly integrated PWM fan speed controller in the top part of the fan shroud. Do nothing and the CNPS10X Extreme's 120mm fan will fall under BIOS control, automatically scaling fan speed from 1000RPM to 2150RPM as needed. Set the fan speed controller and the heatsink operates in one of three fan-duty modes, or responds to the turn of a dial to the exact fan velocity you want.