Ill second this.
Ive got 4 of them in my 900. They work great for cheap fans, good airflow and quiet. I got them all for 5.99 each at Frys. Ive got mine on a fan controller for maximum silence, I run them at 1500 rpm and I cannot hear my PC over the sound of my ceiling fan. They do have a slight click when undervolted, but you can only hear it if you are right up on the fan and adjusting the voltage.













