

🛠️ Small fan, big impact — cool smarter, not louder!
The Noctua NF-A4x20 FLX is a premium 40x40x20 mm computer case fan delivering up to 5000 RPM with ultra-quiet 14.9 dB(A) noise levels. Designed for compact spaces like 1U servers, network switches, and NAS devices, it features advanced acoustic optimization and Flow Acceleration Channels for superior airflow of 9.4 m³/h. The FLX version offers three speed settings via Low-Noise Adaptors, plus a comprehensive installation kit including anti-vibration mounts and proprietary connectors, ensuring effortless, silent cooling tailored to professional setups.































| ASIN | B072JK9GX6 |
| Air Flow Capacity | 9.4 Cubic Meters Per Hour |
| Best Sellers Rank | #81 in Computer Case Fans |
| Brand | Noctua |
| Compatible Devices | Desktop |
| Cooling Method | Air |
| Date First Available | July 12, 2017 |
| Is Discontinued By Manufacturer | No |
| Item Weight | 6 ounces |
| Item model number | NF-A4x20 FLX |
| Manufacturer | Noctua |
| Material | Fibre-glass reinforced PBT |
| Maximum Rotational Speed | 5000 RPM |
| Noise Level | 14.9 Decibels |
| Power Connector Type | 3-Pin |
| Product Dimensions | 1.57"L x 1.57"W x 0.79"H |
| UPC | 841500110116 |
| Voltage | 12 Volts |
P**K
Perfect for network switch fan replacement projects - Noctua is an amazing company
I purchased an unmanaged 5 port, 10gbe / 100gbs network switch to put in my makeshift networking closet. Closet is about 6 feet from my work station. Switch works GREAT, but has a 40mm fan that is legit 40db loud on the tech sheet for it but more like 50db in real life which is like having a conversation with a person loud. To remedy the issue, I purchased this fan. The fan itself is of the high quality and acumen for brown color tones one would expect from Noctua, so I'm not even going to touch on that. What is the most amazing about this purchase is everything else it comes with the kit and how Noctua caters to the primary use case for their customers here. My OEM fan has a 2 pin connector to the PCB. Noctua includes a converter so you can splice the OEM 2 pin together with the converter that plugs into the 3 pin coming from the fan. In addition, Noctua provides 3 tool-less (mostly) connectors for the splice. When you crush them down it squirts some kind of non conductive oil into the connections to protect it from water and dust. Made by 3M, but nevertheless a WELL thought out solution to include for their customers. Running at 4000+ rpm is extremely unnecessary for this network switch & since silence is the name of the game for me a way to reduce RPM without implementing a PWM controller in my limited space configuration. Another whammy from Noctua for this problem. Two RPM cables are included that step down the rpm without the need for a separate controller. I used the ultra low noise cable. It reduce the noise some, but the fan itself made such a difference that alone should do the trick for most people. I've purchased a lot of PC components and networking hardware over the years. Not sure I've ever felt like a company thought this much about their customer for something that costs such a small amount of money. The time and frustration they saved me is immeasurable and priceless. Good job Noctua :-)
E**N
Fits the Icom IC-2730B
The IC-2730 is a great radio, but it has a fan that comes on as soon as you transmit in high power mode. Then it stays on for a minute or more even if you only keyed up for a second or so. And the fan is loud! In medium power mode, it takes 10 or 15 seconds for the fan to come on and then it stays on for a while. This Noctua fan fits the radio perfectly and is so quiet that it is hard to tell if it is running or not. That is no exaggeration. Installation is easy but requires that the connector from the old fan be spliced onto the wires of the new fan. The new fan comes with solderless connectors to do this, but they are too big, so I just cut the wires and spliced them, soldering the connections. Just ignore the yellow wire from the fan; it is not needed in this radio. Note that the fan blows into the radio, not out. This easy modification makes a great radio better.
J**X
Functional with good acoustics
While not as quiet as other Noctua fans (obviously, given it's size and RPM), it's a huge improvement over other similarly specced server fans. It moves a good amount of air while maintaining a sound profile that lacks any of the whining or high-pitched hums that other 40mm fans tend to have. If you're concerned about sound and/or build quality, this is a solid pick.
L**N
A fan that lives up to Noctua’s reputation
I recently upgraded the case for my computer. The new case had much quieter fans than my old one. Happy as a peacock, I set about using it, only to be disturbed by a high pitched whine that quickly got on my nerves. A little investigation and I discovered that the stock 40mm fan that helped cool a component on my motherboard was the culprit. So I went looking for a replacement. Enter the Noctua fan. I was familiar with Noctua from research I’d done about CPU cooler fans a few years ago. Their reputation is very good. That inspired my purchase of this fan over other less expensive brands. I wasn’t disappointed. This fan is quiet. There is very little noise other than the sound of air moving through it. Even that is minimal. Obviously, that is exactly what I was looking for, so it fits the bill perfectly. I wanted a fan that wouldn't disturb the peace. This one is quiet as a mouse. Overview: The fan comes with a standard 3 pin connector that is common on many motherboards and electronics. It also has an assortment of additional items in the box. This includes a short extension cable, low noise adapters that reduce the speed of the fan and 4 omnijon clips , so you can easily remove the included 3 pin connector and connect a new one if needed. A set of case screws and anti-vibration mounts are also included in the box. The fan itself has silicon pads on the corners to help cut down on vibration. Unlike other reviewers, I had no issue with them falling off. I did not use any of the mounting options provided in the box as I simply used the mounting solution my mother board already provided. I suspect that the anti-vibration mounts would be one time use. They’re shaped like Christmas tree clips and would probably get shredded when removed. Another bonus is that it has a nicely presented set of instructions explaining how to use the adapters and silicon mounts. Bottom line: The packaging for this fan is crazy. It comes in a double book fold cardboard box with a molded plastic tray. I guess they’re trying to give the impression of quality with the packaging, but it really seems like overkill for a product that cost only 14 dollars. Noctua wants its customers to feel like they got a quality product by providing one and packaging it like one. Well, it worked. This is a great little fan.
J**A
Super case fan for efficient & quiet operation
These fans are super quiet and efficient. Extremely well made using quality components and at a very affordable price. Comes with a wide range of attachment options. Have bought two but will buy some more to replace all my existing computer related case fans.
A**L
Super silent, buy it
A**R
I used this to replace the fan in my hub. Keeps things cool.
C**N
I have fitted these, blowing, into my Ubiquiti UniFi USG-Pro-4 and I can report the high pitch whine is now gone. Pretty handy when you don't have a rack out of the way of habitual areas! Only been installed an hour but so far so good, and I chose to use the noise suppression mounts, they aren't recommended for this application but I wanted to try it and the resonance from the metal cover is now much more subtle. Running these fans without a cover show they are actually virtually silent, but obviously, it's not recommended to run this device with the cover off (airflow etc)!
W**S
Its nice for the small pc
F**Z
Desde el empaquetado del producto se siente la calidad, viene con todos sus accesorios, se siente de muy buena calidad. Es silencioso y tiene buen caudal de aire. Lo usé para reemplazar el ventilador de un XVR Dahua, el ventilador original es de 2 pines, este ventilador noctua viene con sus accesorios para poder hacerlo de 3 pines a 2 pines. Los resultados fueron demasiado superiores al ventilador original, mucho más caudal de aire y sobre todo muy silencioso. Estoy muy satisfecho con la compra.
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