

🌀 Silence meets power: The ultimate compact cooling upgrade
The Noctua NF-A4x20 FLX is a premium 40x40x20mm computer case fan engineered for high-performance cooling in tight spaces. Featuring a max speed of 5000 RPM, ultra-quiet operation at just 14.9 dB(A), and advanced aerodynamic technologies like Flow Acceleration Channels and SSO2 bearings, it delivers efficient airflow with minimal noise. The FLX version offers three speed settings via included Low-Noise Adaptors, plus anti-vibration mounts and an OmniJoin adaptor set for easy installation in network equipment, desktops, and specialized devices. Backed by a 6-year warranty, it’s the go-to choice for professionals demanding silent, reliable cooling.































| ASIN | B072JK9GX6 |
| Air Flow Capacity | 9.4 Cubic Meters Per Hour |
| Best Sellers Rank | #76 in Computer Case Fans |
| Brand Name | Noctua |
| Compatible Devices | Desktop |
| Cooling Method | Air |
| Customer Reviews | 4.8 4.8 out of 5 stars (2,511) |
| Included Components | 1 |
| Item Dimensions L x W x H | 1.57"L x 1.57"W x 0.79"H |
| Manufacturer | Noctua |
| Material Type | Fibre-glass reinforced PBT |
| Maximum Rotational Speed | 5000 RPM |
| Noise Level | 14.9 Decibels |
| Power Connector Type | 3-Pin |
| UPC | 841500110116 |
| Unit Count | 1.0 Count |
| Voltage | 12 Volts |
| Warranty Description | 6 year manufacturer’s warranty |
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.
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.
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
R**S
Fan was so quiet I had to visually check to make sure it was spinning. It comes with both a low noise adapter and an ultra low noise adapter. I can't imagine needing them since it is barely audible at full speed. Certainly the quietest fan this size that I've ever encountered.
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