Featuring 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 2100rpm. Its superb running smoothness, SSO2 bearing and Noctua’s trusted premium quality make it an elite choice for the highest demands.Reduced motor hub sizeThanks to its streamlined, compact motor design, the NF-A6x25's motor hub is smaller than with conventional 6cm fans. This allows for more blade surface area and thus contributes to the NF-A6x25's superior airflow and pressure performance.Flow Acceleration ChannelsThe 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.AAO frameNoctua'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 DesignNoctua'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 MicrostructuresWith 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 PadsIntegrated 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.SSO2 bearingThe NF-A6x25 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.Custom-designed PWM IC with SCDSupporting fully automatic PWM speed control, the NF-A6x25 PWM uses Noctua's 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 low speeds.Stops at 0% PWMWhen 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.Low-Noise AdaptorThe NF-A6x25 PWM is supplied with a (L.N.A.) that reduces the maximum fan speed from 3000 to 2100rpm. The L.N.A. can be used either to run the fan at a fixed speed of 2100rpm or to cap the maximum speed when using automatic PWM control.Extensive cabling optionsThe 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 NF-A6x25 PWM fan to the same PWM fan header for automatic control.6-year manufacturer’s warrantyNoctua fans are renowned for their impeccable quality and outstanding longevity. Like all Noctua fans, the NF-A6x25 features an MTTF of more than 150.000 hours rating and comes with a full 6-year manufacturer’s warranty.