Featuring advanced aerodynamic design measures such as Flow Acceleration Channels and Noctua’s AAO frame the NF-A4x20 is a highly optimised premium-quality quiet fan in size 40x20mm. 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.

40x20mm size
Compared to Noctua’s award-winning NF-A4x10 the NF-A4x20 is twice as thick which allows for increased static pressure performance and makes the NF-A4x20 ideal for demanding applications with high flow resistance.

Flow Acceleration Channels
The NF-A4x20 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
Noctuas AAO (Advanced Acoustic Optimisation) frames feature integrated anti-vibration pads as well as Noctuas proprietary Stepped Inlet Design and Inner Surface Microstructures both of which further refine the fans performance/noise efficiency.

Stepped Inlet Design
Noctuas 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.

SSO2 bearing
The NF-A4x20 features the further optimised second generation of Noctuas 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 SCD
Supporting fully automatic PWM speed control the fan uses Noctuas 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.

Low-Noise Adaptor
The NF-A4x20 PWM is supplied with a (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 comes with Noctuas OmniJoin™ adaptor set. Just cut the original fans cable fix it to the adaptor using the supplied 3M Scotchlok™ connectors and you can plug the NF-A4x20 to proprietary fan headers!

Extensive cabling options
The fans 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.

FAN Specification
Size40x40x20 mm
Mounting hole spacing32x32 mm
Connector & pin-configuration4-pin PWM
Cable length20cm + 30cm NA-EC1 extension cable
BearingSSO2
Blade geometryA-Series with Flow Acceleration Channels
Frame technologyAAO (Advanced Acoustic Optimisation)
Rotational speed (+/- 10%)5000 RPM
Rotational speed with L.N.A. (+/- 10%)4400 RPM
Min. rotational speed (PWM +/-20%)1200 RPM
Airflow94 m³/h
Airflow with L.N.A.83 m³/h
Acoustical noise149 dB(A)
Acoustical noise with L.N.A.122 dB(A)
Static pressure226 mm H₂O
Static pressure with L.N.A.175 mm H₂O
Max. input power06 W
Max. input current005 A
Operating voltage12 V
Voltage PWM signal5 V
MTTF> 150.000 h
Scope of delivery
Low-Noise Adaptor (L.N.A.)
4-pin y-cable
30cm extension cable
OmniJoin™ adaptor set
NA-AV3 anti-vibration mounts
Fan screws
Warranty6 years