Noctua NF-A6x25 PWM 60mm Low Noise FannnFeaturing advanced aerodynamic design measures such as Flow Acceleration Channels and Noctua's AAO frame the NF-A6x25 is a highly optimised premium quality quiet fan in 60x25mm size. The PWM version sports Noctua's custom designed NE-FD1 IC for fully automatic speed control via 4-pin fan headers and comes with a Low-Noise-Adaptor to reduce the maximum speed during PWM control from 3000 to 2300 RPM. Its superb running smoothness SSO2 bearing and Noctuau2019s trusted premium quality make it an elite choice for the highest demands.nnFlow Acceleration Channels The NF-A6x25 impeller features suction side Flow Acceleration Channels. By speeding up the airflow at the crucial outer blade regions this measure reduces suction side flow separation and thus leads to better efficiency and lower vortex noise.nReduced Motor Hub Size Thanks to its streamlined compact motor design the NF-A6x25's motor hub is smaller than with conventional 6cm fans.