Noctua NF-A4x10 PWM 12V 5000RPM 40x10mm Quiet Cooling Fan\n\nFeaturing advanced aerodynamic design measures such as Flow Acceleration Channels and Noctua's AAO frame; the NF-A4x10 is an award-winning; premium-quality quiet fan in size 40x10mm. 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 as well as an OmniJoin Adaptor Set for easy connection to proprietary fan headers. Its superb running smoothness; reference-class SSO2 bearing and Noctua's trusted premium quality make it an elite choice for the highest demands.\n\n Reduced motor hub size Thanks to its streamlined; compact motor design; the NF-A4x10's motor hub is smaller than with conventional 4cm fans. This allows for more blade surface area and thus contributes to the NF-A4x10's superior airflow and pressure performance.\nFlow Acceleration Channels The NF-A4x10 impeller features suction side Flow Acceleration Channels. By speedi;