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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.
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-RC7 Low-Noise Adaptor (L.N.A)
- NA-YC1 4-pin PWM y-cable
- NA-EC1 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.
lyrikal
Reviewed in the United States on March 2, 2025
Works well, fits right into the spot the old 40x40x20 mm fan went. That thing was noisy as heck on start up. Board inside the TEG-S708 has 3-pin fan port, so voltage line controls rpm, but this 4-pin from Noctua works just fine in the 3-pin port. Fan still changes rpm speed based on voltage line. Silent as heck. It does move less air than stock, but still enough air over the 10G switch heat sinks to cool it down. Laser readings on heat sinks were under 44C after couple hours of power on.
Steve
Reviewed in Canada on February 1, 2025
extremely quiet cant even tell its on even tho its running at full rpm.
Tsab
Reviewed in the United States on January 27, 2025
Nice and quiet
will
Reviewed in the United States on January 24, 2025
Bought this to replace the stock fan in a MikroTik CRS310-8G+2S+. This noctua fan at max rpm is 1/4 the volume of the stock fan at idle temps. The difference is crazy. Airflow seems to be better to as the temps are lower at the same rpm compared to stock as well. High quality, excellent performance, and absolutely no noise.
Jeremy Kenney
Reviewed in the United States on July 24, 2024
I have a home lab and running a Dell 2048 datacenter switch. the OEM fans are very loud so i bought this one to replace them. it works great and came with the right wiring/adapter i needed. I highly recommend if you are looking to quiet down some equipment (servers, switches, etc.)
Jakir Basha
Reviewed in India on July 22, 2024
Product quality and packaging is good.i wood recommend buying from desertcart site, the actual sellers website from which i got for 2399 rs.
Itozzz
Reviewed in Spain on December 4, 2024
Noctua es símbolo de calidad aunque un poco caro son sus productos.Para Canarias no recomiendo los envíos premium ya que tardan lo mismo que los normales.
Justin H.
Reviewed in the United States on January 21, 2024
I recently added the Noctua NF-A4x20 PWM to my server setup, and the performance of this 40x20mm fan has left me thoroughly impressed. Noctua's reputation for premium quality is well-deserved, and this fan is no exception.Firstly, the build quality is exceptional. The brown color may be unconventional, but it's a symbol of Noctua's commitment to quality. The construction feels robust, and the attention to detail is evident. This fan exudes durability, assuring me that it can handle continuous operation in a server environment.Now, let's talk about the noise level—or rather, the lack of it. This fan is remarkably quiet, especially considering its size. Noctua's focus on providing a quiet solution without sacrificing performance is evident here. Whether my server is working at full capacity or idling, the NF-A4x20 PWM operates silently, contributing to a peaceful and distraction-free environment.The PWM functionality is a standout feature. The fan's speed is dynamically controlled based on the system's temperature needs, ensuring optimal cooling without unnecessary noise. This adaptability is a game-changer for maintaining the right balance between temperature control and acoustics.Installation was a breeze, thanks to the included accessories and clear instructions. The fan integrates seamlessly into my server setup, and the 4-pin connector allows for precise control over its operation.The performance, reliability, and quiet operation make it a top-tier choice for anyone seeking a compact, high-quality fan for their server. In my book, it's a solid 5-star product, and I wouldn't hesitate to recommend it to anyone looking to add performance and lower the noise level of their server or PC.
Duane L. Mckinney
Reviewed in the United States on February 17, 2023
These don't move as much air as the fans they replaced. I read another reviewer that said the point of these is so that you don't have something that sounds like a terminator moving. Very accurate, and is what made me purchase. I don't care about the less air flow, because it is located close to people, so the temperature will be pretty steady and reasonable. I can not hear any noise at all unless I get within 2-3 feet of it, and even with my ear right next to the fan, it is very quiet.I wish that they labeled the cables somewhere. I had to swap 2 of them, but it was a little trial and error. Having a diagram of what each color is (power, ground, pcm, rpm) would have been nice. It was nice that they included some splice connectors to make the job easy.I would prefer less packaging. This was a retail type package and looked very pretty, but for a drop ship item, it isn't needed.
Jestebankof
Reviewed in Mexico on September 30, 2021
Calidad Noctua. Para una fuente de poder ITX buscaba un ventilador con alto rendimiento y muy silencioso y Noctua es el ganador. En cuanto a presentacion desde el empaque notas la calidad premium de los materiales, la variedad de accesorios incluidos, la calidad del cable... En cuanto a rendimiento practicamente es imperceptible el ruido para la cantidad de aire que genera. Comparandolo con un Nidec no tiene nada que hacer el noctua, pero Nidec hace ruido y vibra como un mototool, aun a bajas RPM, en entornos industriales donde no importa el ruido Nidec es superior pues tiene mayor rendimiento ya que gira a mas altas RPM, Pero esque el noctua al 100% hace menos ruido que el Nidec al minimo que deja el PWM y no vibra nada, a similares RPM mueven el mismo aire, pero Noctua no se escucha nada, y nidec pues parece un mini taladro. Ni hablar, Noctua no tiene rival en relacion Rendimiento-Silencio.
Ian Timothy
Reviewed in the United Kingdom on September 17, 2021
Ticks every box and is brilliant value for money
John W. Daniels
Reviewed in the United States on April 15, 2018
With over a dozen NF-A4x10's in use here on various systems, I was shocked to find the NF-A4x20 is MUCH much quieter than the NF-A4x10, in fact it is nearly inaudible. (A4x10 is still a great product, but there is not much they can do about such a thin fan).Initially I was a bit concerned at the fan blade design of 7 instead of the usual 5 blade in this form factor, however it appears to be doing quite well. In fact, I believe this design is better suited to lower RPM fans for generating more static pressure. The intake side of the fan is also somewhat recessed, which increases it's ability to generate a stable vortex when installed in environments with moderate intake restriction (though all fans are generally designed for static pressure on the output side and not the intake side, so they often are louder in these situations.)While it probably can't replace most beefy 40x38mm server fans, it CAN if your cooling requirements are much lower than your chassis was designed for (but keep in mind that small ICs and other components often rely on very high airflow in small servers, although this can be remedied by applying small heatsinks to any hot spots).I'm currently using this NF-A4x20 in a 900w Flex-ATX server power supply which originally had an obnoxiously loud 13k RPM 40mmx38mm fan. I definitely would not recommend that others try this too (unless you REALLY know what you're doing), but I knew I could get away with it since I have never loaded the PSU past 40% and the chassis has high airflow already with additional (Noctua) fans added to quiet it down.In conclusion, these surprised me with their silent performance - Noctua has done it again. It should be noted, however, that these are probably intended for and better suited for adding extra cooling to network switches and other small devices (maybe 3d printers, but I don't have any expertise there). If the device in question had a similar fan, then it's probably fine to replace with these - otherwise I'd say your mileage may vary if intending to replace very high RPM 40mm fans.[Disclaimer: Review written by item recipient, not by above account holder name]
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