Noiseblocker NB-ELOOP B12 PS fan (120mm PWM) (Accessories)
Operate the fan sitting on a FX6100 on a Alpenföhn large Clock'ner. In idle it rotates at 760 rev / min and is inaudible. In load the fan turns faster and is then heard. Think it is because of its proximity to the cooler, where the air will break.