"Right now it's time to get back on track as we evaluate the Thermalfly F1-IACSHA, a large fully copper heatsink which combines a 63mm diameter squirrel cage fan and a unique L-shaped copper cooling fin array. This heatsink has a couple attributes we've never seen before in a desktop cooler...

The Thermalfly F1-IACSHA is equipped with a four-pin Pulse Width Modulation (PWM) squirrel cage fan that goes one step further than BIOS determined fan speed control. At the base of the F1-IACSHA heatsink is its very own thermistor temperature sensor, taped to the top of the copper processor block with a small aluminum sticker. The thermistor provides accurate temperature readings to the fan, and this determines how quickly it spins at any given moment."