Featuring advanced aerodynamic design measures such as Flow Acceleration Channels and Noctuas AAO frame. the NF-A4x10 is an award-winning. premium-quality quiet fan in size 40x10mm. The PWM version sports Noctuas 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 Noctuas trusted premium quality make it an elite choice for the highest demands. Award-winning NF-A4x10 design Having received more than 50 awards and recommendations from the international press. Noctuas NF-A4x10 has become a proven premium choice for 40mm cooling needs. Its renowned efficiency has convinced tens of thousands of customers all over the world. 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. Flow Acceleration Channels The NF-A4x10 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. AAO frame Noctua's AAO (Advanced Acoustic Optimisation) frames feature integrated anti-vibration pads as well as Noctua's proprietary Stepped Inlet Design and Inner Surface Microstructures. both of which further refine the fan's performance/noise efficiency. Stepped Inlet Design Noctua's Stepped Inlet Design adds turbulence to the influx in order to facilitate the transition from laminar flow to turbulent flow. which reduces tonal intake noise. improves flow attachment and increases suction capacity. especially in space-restricted environments. Inner Surface Microstructures With the tips of the fan blades ploughing through the boundary layer created by the Inner Surface Microstructures. flow separation from the suction side of the blades is significantly suppressed. which results in reduced blade passing noise and improved airflow and pressure efficiency. Integrated Anti-Vibration Pads Integrated Anti-Vibration Pads made from extra-soft silicone minimise the transmission of minute vibrations while maintaining full compatibility with all standard mounting systems and fan clips used on heatsinks. Custom-designed PWM IC with SCD Supporting fully automatic PWM speed control. the NF-A4x10 PWM uses Noctua's novel. custom-designed NE-FD1 PWM IC that integrates Smooth Commutation Drive (SCD) technology. By providing smoother torque impulses. SCD suppresses PWM switching noises and thus makes the fan quieter at lower speeds. Stops at 0% PWM When the fan is set to 0% PWM duty cycle by the motherboard or PWM fan controller. it will stop. This makes it ideal for creating setups with semi-passive cooling that automatically turn the fans off and thus run completely silent at idle if thermals allow. SSO2 Bearing The NF-A4x10 features the further optimised second generation of Noctua's renowned. time-tested SSO bearing. With SSO2. the rear magnet is placed closer to the axis to provide even better stabilisation. precision and durability. Low-Noise Adaptor The NF-A4x10 PWM is supplied with a Low-Noise Adaptor (L.N.A.) that reduces the maximum fan speed from 5000 to 3700rpm. The L.N.A. can be used either to run the fan at a fixed speed of 3700rpm or to cap the maximum speed when using automatic PWM control. OmniJoin Adaptor Set Many devices featuring 40mm fans use proprietary fan headers. so the NF-A4x10 comes with Noctua's OmniJoin adaptor set. Just cut the original fan's cable. fix it to the adaptor using the supplied 3M Scotchlok connectors and you can plug the NF-A4x10 to proprietary fan headers! Extensive cabling options The fan's short 20cm primary cable minimises cable clutter in typical applications while the supplied 30cm extension provides extended reach when necessary. Both cables are fully sleeved and a 4-pin y-cable allows the connection of a second fan to the same PWM fan header for automatic control. 6-year manufacturers warranty Noctua fans are renowned for their impeccable quality and outstanding longevity. Like all Noctua fans. the NF-A4x10 features an MTTF of more than 150.000 hours rating and comes with a full 6-year manufacturer's warranty.