Featuring advanced aerodynamic design measures such as Flow Acceleration Channels and Noctua’s AAO frame, the NF-A4x20 PWM is a highly optimized, premium-quality quiet fan in size 40x20mm.
The PWM version provides 5000/4400/3700rpm speed settings via the supplied Low-Noise Adaptors and includes the 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.
Compared to Noctua’s award-winning NF-A4x10, the NF-A4x20 PWM is twice as thick, which allows for increased static pressure performance and makes the NF-A4x20 PWM ideal for demanding applications with high flow resistance.
Flow Acceleration Channels
The NF-A4x20 PWM 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.
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 plowing 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 minimize the transmission of minute vibrations while maintaining full compatibility with all standard mounting systems and fan clips used on heatsinks.
The NF-A4x20 PWM features the further optimized 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 stabilization, precision, and durability.
Custom-designed PWM IC with SCD
Supporting fully automatic PWM speed control, the fan 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% 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.
The NF-A4x20 PWM is supplied with an (L.N.A.) that reduces the maximum fan speed from 5000 to 4400rpm. The L.N.A. can be used either to run the fan at a fixed speed of 4400rpm 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-A4x20 PWM comes with Noctua’s OmniJoin™ adaptor set. Just cut the original fan’s cable, fix it to the adaptor using the supplied cable connectors and you can plug the NF-A4x20 PWM into proprietary fan headers!
Extensive cabling options
The fan’s short 20cm primary cable minimizes cable clutter in typical applications while the supplied 30cm extension provides extended reach when necessary. Both cables are fully sleeved and the supplied 3:4 pin adaptor allows the connection of the fan directly to the power supply.
6-year manufacturer’s warranty
Noctua fans are renowned for their impeccable quality and outstanding longevity. Like all Noctua fans, the NF-A4x20 PWM features an MTTF of more than 150.000 hours rating and comes with a full 6-year manufacturer’s warranty.