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Noctua NF-A4x20 FLX, Premium Quiet Fan, 3-Pin (40x20mm, Brown)

In stock.
Ships from United States.
  • PWM
  • FLX
  • 5V PWM
  • Premium quiet fan, 40x40x20 mm, 12V, 3-pin Molex, 5000/4400/3700 RPM, max. 14.9 dB(A), >150,000 h MTTF
  • Award-winning A-series design with Flow Acceleration Channels and Advanced Acoustic Optimisation frame for superior quiet cooling performance
  • 40x20mm size ideal for 1U applications or replacing fans in network and storage equipment (routers, switches, NAS etc.) or other devices such as DVRs
  • 3-pin FLX version provides 5000/4400/3700rpm speed settings via Low-Noise Adaptors to fine-tune the fan for maximum airflow or near-silent operation
  • Includes anti-vibration mounts, fan screws, extension cable and OmniJoin adaptor set for connecting the fan to proprietary fan headers

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 FLX 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.


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.  
SSO2 Bearing
The NF-A4x20 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.  
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.  
Scope of delivery
  • NA-RC10 Low-Noise Adaptor (L.N.A)
  • NA-RC12 Ultra-Low-Noise Adaptor (U.L.N.A)
  • NA-EC2 30cm extension cable
  • OmniJoin adaptor set
  • 4x NA-AV3 anti-vibration mounts
  • Fan screws
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.


Connector 4-pin PWM 3-pin 4-pin PWM 3-pin
Voltage 12V 12V 5V 5V
RPM Max: 5000 / Min: 1200 5000 Max: 5000 / Min: 1100 5000
RPM with L.N.A. 4400 4400 - -
RPM with U.L.N.A. - 3700 - -
Acoustical Noise 14,9 dB(A) 14,9 dB(A) 14,9 dB(A) 14,9 dB(A)
Acoustical Noise with L.N.A. 12,2 dB(A) 12,2 dB(A) - -
Acoustical Noise with U.L.N.A. - 8,5 dB(A) - -
Size 40x40x20 mm 40x40x20 mm 40x40x20 mm 40x40x20 mm
Colour Brown & Beige Brown & Beige Brown & Beige Brown & Beige

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