Fan Noctua 40x40x20mm - NF-A4x20-FLX

This Noctua NF-A4x20-FLX is a 40x40x20 mm fan, aimed at specific scenarios – compact cases, small chassis, networking devices, routers, NAS units, and all kinds of small hardware where space is limited, but you want something reliable and quiet. The operating range of 3700-5000 RPM provides flexibility between cooling and silence, while the low noise level of 14.9 dBA is a serious plus for a small fan. The connector is a standard 3 PIN, so it easily integrates into most systems. Add the typical Noctua durability and you get a fan that won't just spin, but will spin long and stable.

What you get
With a size of 40 x 40 x 20 mm, the NF-A4x20-FLX fits where a normal 80 or 120 mm fan has no chance – mini ITX cases, media centers, or as a replacement for noisy stock fans in small devices. The thickness of 20 mm compared to the standard 10 mm in this format allows it to maintain a more meaningful airflow of 5.53 CFM / 9.4 m3/h, which is critical in closed and warm volumes. Thanks to the SSO2 bearing and MTBF 150000 hours, you can leave it running 24/7 without worrying about quick wear – especially important for devices that you don't want to tinker with often. The consumption is super low – only 0.6 W at 12 V and 0.05 A, which is convenient if you're connecting it to a limited power budget or controller. The low noise level makes it a sensible choice for systems in a living room or office, where every whir is heard.

• Compact form factor 40 x 40 x 20 mm, suitable for small cases, embedded systems, and replacement of factory fans in devices.
• Wide range of 3700-5000 RPM, giving you the choice between quieter operation and more aggressive cooling as needed.
• Airflow of 5.53 CFM / 9.4 m3/h, optimized for small size, to expel warm air from tight spaces.
• Low noise level of 14.9 dBA, which is a serious advantage for a 40 mm fan in systems that operate close to you.
• Durable SSO2 Bearing and MTBF 150000 hours, ensuring long life and reliable 24/7 operation.
• Standard 3 PIN connector for easy compatibility with most motherboards and fan controllers.
• Very low consumption – only 0.6 W at 12 V and 0.05 A, power-saving and suitable for sensitive systems.
• The classic brown color of Noctua clearly shows what you have inside, even in a small modded case.
• Long 72 months warranty, reinforcing the idea of serious resource and reliability.

Who it is suitable for
It is suitable if you are building or maintaining compact systems – mini PCs, HTPCs, networking devices, NAS boxes, or simply want a quality and quiet alternative to an OEM 40 mm fan. It is not for classic gaming cooling of a case in mid or full tower format – there, larger diameters make much more sense.

The combination of small size, low noise, and serious MTBF makes the Noctua NF-A4x20-FLX one of those “install and forget” solutions. If you need a reliable 40 mm fan that won't scream in your ears and will last for years, this model covers exactly that.