40x40x20 mm, 4-Pin PWM, 1200-5000 RPM, 12.2/14.9 dB, 0.6 W, 5-12 V
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
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 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 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 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.
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 Noctua's OmniJoin™ adaptor set. Just cut the original fan's 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 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 fan to the same PWM fan header for automatic control.
6-year manufacturer’s warranty
Noctua fans are renowned for their impeccable quality and outstanding longevity. Like all Noctua fans, the NF-A4x20 features an MTTF of more than 150.000 hours rating and comes with a full 6-year manufacturer’s warranty.
| Performance |
| Pulse-width modulation (PWM) support |
Yes |
| Maximum air pressure |
2.26 mmH2O |
| Minimum air pressure |
1.75 mmH2O |
| Airflow with LNA (max) |
8.3 m³/h |
| Airflow |
9.4 m³/h |
| Noise level with LNA (max) |
12.2 dB |
| Noise level (high speed) |
14.9 dB |
| Rotational speed with LNA (max) |
4400 RPM |
| Rotational speed (max) |
5000 RPM |
| Rotational speed (min) |
1200 RPM |
| Compatible processor series |
Not supported |
| Supported processor sockets |
Not supported |
| Fan diameter |
4 cm |
| Type |
Fan |
| Suitable location |
Computer case |
| Design |
| Fan connector |
4-pin |
| Product colour |
Beige, Brown |
| Power |
| Maximum current |
0.05 A |
| Voltage |
5 - 12 V |
| Power supply |
0.6 W |
| Weight & dimensions |
| Height |
20 mm |
| Depth |
40 mm |
| Width |
40 mm |
| Packaging content |
| Low-noise adaptor (LNA) |
Yes |
| Screws included |
Yes |
| Cables included |
Fan |
| Other features |
| Mean time to failure (MTTF) |
150000 h |
| Mounting hole pattern (W x D) |
32 x 32 mm |
| Logistics data |
| Harmonized System (HS) code |
84733080 |

Have you ever thought of trading in your old smartphone?
Recycling your phone is a great way to help the environment and earn some extra money, and Clove Technology offers a recycling programme that pays you for your old phone(s)!
So if you're about to buy a new phone from us, or you've recently bought one, why not sell us the handset you no longer need?
How much will you offer for my phone?
That depends on its age and condition. More recent phones generally have a higher value than old ones, but other factors can affect value. These include if the phone is working or not and its network lock status. Fully working phones with an unlocked network status will command a higher value if they are in good condition.
We pledge to beat the major recycling services operating in the UK on the price they offer for your
How do I get my phone(s) back to you?
On our recycling site SEARCH, for your phone and provide details of its status and condition. We will then offer you a price for your phone. If you choose the option to Sell Now, a recycling pack to you for returning your phone.
Alternatively, you can call our recycling team on 0330 1180686, choosing option 2.