NF-A4x20 FLX, High-Performance Quiet Fan 40mm

Works great, same airflow but much quieter as other brands. Comes with all the adapters to fit perfectly in any device. Highly recommend.

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 while back I had picked up one of those popular multi-drive docks for the SSDs in my desktop. It's a popular dock that will go nameless for this review. The worst thing about it, the reviews warned, was the fan. It wasn't bad at first but over time had gotten quite noisy - enough that I went searching for a replacement. I already use one of Noctua's CPU coolers and it's awesome so this NF-A4x20 FLX was kind of a no-brainer. It does no disappoint! The dock's quieter than ever. What's more, each drive in the dock runs about a degree cooler than before with no settings changes. Everyone knows that heat is the enemy so this is a small but measurable win. Now, the bad - at least for my particular application. None of the mounting screws supplied with the fan would fit. It's not Noctua's fault. The original fan was perhaps half the thickness of this one. The longer supplied screws were a bit too long - there's a circuit board about 4 millimeters behind the mounting holes in the doc, so screw length was critical. I ended up cutting screws from my parts bin to the exact length I needed. I really wish I could have used the rubber pull-through mounts Noctua included because they would have surely quieted things down even more. I think I could if I wasn't too lazy to tear apart the dock to customize the fan mount surface. Maybe for the future. So I've been using this fan now for a little better than a month and it's as quiet as ever. If you can manage the thickness, this is an awesome 40 millimeter square replacement fan.

This replaced a fan that went bad. Didn't need to use any of the helpful accessories - just plugged right in and worked fine. Very quiet.

I have bought lots of these over the years, and as is typical for Noctua you're getting a high quality product that is QUIET. I bought these fans to replace the ones on a network switch since I know Noctua is quieter, and while they did not work on the switch I intended them for because the switch is wired different, I used them in another one and they work perfectly. Yes some may say they don't flow as much as the industrial grade, super loud fans that come with them, but in a home environment that matters much less and I'd rather have peace and quiet thanks to Noctua. That being said, this is a small fan, small fans spin faster and are louder by nature, so I'd still recommend either using the included Low Noise Adapter Cable (labeled in the box), or implementing some sort of fan control. At 50% speed these are basically whisper quiet, and move some decent air. I also have the PWM versions of these which are easier to control for speed, but you get the idea. One small con is that the rubber dampener things that come with these are basically useless because they don't seem to stay in on the small fans. I've used them on the 120mm fans and they work fine but for these they don't really work as well and the fan slips off.

Used as a replacement for the old and loud Delta EFB0412MD-R00 3-Pin fan that started to make rattling noise intermittently on my Cisco SG200-26P PoE Switch. I'm guessing the bearings on it were the cause and it gave me a reason to look for a replacement. After doing some research online and for my home use application, settled on this Noctua NF-A4x20 FLX fan and it worked after some modding and is noticeably quieter. I've read people using the comparable Noctua PWM fan as a replacement but that's a 4 pin fan as opposed to this 3 pin fan. Looking at the Noctua fan schematics, the additional wires on their fans are for the RPM speed signal as well as the PWM signal. These additional wires should NOT be connected to the Cisco switch as the third blue wire found on the Delta fan as well as the fan header is meant for the Locked Rotor Sensor wire that these Noctua fans don't have (wish they sold one so you didn't have to mod these). Be aware that the pin layout on the fan header of the Cisco motherboard is different than the pinout of the fan so it's not as simple as just plugging it in. I used the included adapter cable with the loose black and red wires along with the OmniJoin adaptors. I snipped the wires from the original Delta fan, connected the black (-) and red (+) wires and it was good to go. A word of caution here with the blue wire as if that's not connected, the switch will think the fan is dead and will throw a fan error. To simply get rid of this error, I just stripped the blue wire and connected it to a nearby ground screw. If you do this, there's no way of it knowing if the fan dies but it's not a big deal for my use. Worked for me after some modding and is quieter. Even if it doesn't push as much air as the original fan, the lower noise is a good compromise for my application. Using this switch to power my PoE cameras and so far so good.

I'm going to start off saying this is my first stand alone Noctua fan I've bought, mainly because I always needed 24V and in this size they don't make one. With that said I've read multiple posts around the interwebs where people have used these 12V fans in a 24V printer with no adverse problems. I decided for $15 it was worth a shot to try and see. In the past I've bought dozens of DC fans from 30mm to 120mm for various applications and most come in somewhat basic packaging. The Noctua very much surprised me as the packaging and presentation was very nice and presented well. I was even more surprised when I opened the package to see all the extras included like wire extensions, in-line speed reducers & anti-vibration mounts. The wires are heat shrinked with abrasion resistant sheathing everywhere else on the wire. Before cutting the wire I first tested it on a 12V DC power supply to check that it worked followed by 24V. It worked fine with both voltages, it might have been a little faster on 24V but it was hard to tell because it's rather quiet on both voltages. After removing some wire wrap I cut the wires to my desired length and crimped then soldered on my 2P JST connector (red & black wires) leaving the yellow wire unconnected and secured under the new heat shrink. I then installed on my printer where it's been in use almost constantly now for 18+ hours and still going strong. I'll continue using this as long as it works and if anything changes from the 24V use, like it dies, I'll update my review commentary. Update 04/28/2022: This fan is still going strong on 24V and easily has 1500hrs on it. I've since bought multiple more fans for other printers and projects all working just as well including in my Voron 2.4 ABBN with no heat creep even though the interwebs all claim the low static pressure will cause your hotend to melt like chocolate in the sun.

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.

Super silent, buy it

I used this to replace the fan in my hub. Keeps things cool.

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)!

Its nice for the small pc

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.