Fan Noctua NF-A4x20 PWM 40 mm, 4-pin PWM, 5–12 V, 1200–5000 RPM, 9.4 m³/h, 14.9 dB, 32×32 mm mounting

The Noctua NF-A4x20 PWM is a compact 40x20mm premium-quality fan engineered for efficient cooling in space-restricted and high-resistance applications. It features an advanced aerodynamic design with Flow Acceleration Channels and Noctua's AAO frame to improve airflow efficiency and reduce noise. The PWM model uses Noctua's custom NE-FD1 PWM IC with Smooth Commutation Drive (SCD) for quiet automatic speed control and is supplied with a Low-Noise Adaptor and an OmniJoin™ adaptor set for flexible connectivity. The fan offers a wide speed range (1200–5000 RPM), high static pressure performance and extensive cabling options, and it is backed by a 6-year manufacturer’s warranty.

Advantages

The NF-A4x20 combines optimized blade and frame features such as Flow Acceleration Channels, Stepped Inlet Design and Inner Surface Microstructures to increase efficiency and lower vortex and intake noises. Its AAO frame integrates soft anti-vibration pads for reduced vibration transmission while maintaining compatibility with standard mounting systems. The refined SSO2 bearing improves stabilization, precision and durability, and the NE-FD1 PWM IC with SCD reduces PWM switching noise for quieter low-speed operation. The included Low-Noise Adaptor, OmniJoin™ adaptor set, sleeved cables and Y-splitter provide flexible installation options.

Suitable for

• Compact computer cases and small form factor (SFF) systems
• Cooling heatsinks and dense radiators with high airflow resistance
• Embedded systems, network equipment and proprietary fan-header devices using 40mm fans

Key specifications

• Size: 40 x 20 mm
• Speed range: 1200–5000 RPM (max), L.N.A. caps max to 4400 RPM
• Airflow: 9.4 m³/h (typical, manufacturer data)
• Static pressure: approx. 1.75–2.26 mmH2O (manufacturer data)
• Voltage: compatible with 5–12 V systems
• Connector: 4-pin PWM; includes OmniJoin™ adaptor set and 4-pin Y-cable
• Cabling: 20 cm primary cable, 30 cm extension, all sleeved
• Bearing: SSO2
• Colour: beige / brown
• Warranty: 6 years; MTTF >150,000 h

How to use

Install the NF-A4x20 PWM in your device using the standard mounting holes or compatible fan clips on heatsinks. Connect the 4-pin PWM connector to a motherboard or controller PWM header for automatic speed control; alternatively use the OmniJoin™ adaptors to connect to proprietary fan headers after attaching the supplied Scotchlok™ connectors to the original cable. Use the included extension cable or the Y-splitter as needed to reach headers or to control a second fan from the same PWM signal. Apply the Low-Noise Adaptor if you want to limit the maximum speed to 4400 RPM or run the fan at that fixed speed.

Recommendations

For optimal performance in restricted airflow environments, orient the fan so that the Stepped Inlet Design faces the intake direction and ensure secure mounting with the integrated anti-vibration pads. Use PWM control for automatic speed scaling and fit the L.N.A. when lower maximum RPM is desired.