NoctuaNF-A4x20 5V, Premium Quiet Fan, 3-Pin, 5V Version (40x20mm, Brown)

I used the noctua fan to replace a loud fan in a network switch. The OmniJoin adapter that was included was easily usable and works well. I had to use the anti-vibration fan connectors because the previous fan screw holes were smaller than the noctua fan screw holes. The anti-vibration fan connectors were installed and trimmed, but the network switch case didn't fit properly over the anti-vibration fan connectors. It had to be shoved on, but it worked out. The fan moves a good amount of air, but not as much as the original fan. This is still enough air to keep the switch cool, while being fairly quiet. The fan is still audible (at 5v constant, non-PWM), but I believe this is mostly due to the design of the case, not the fan's fault. The box is a bit overkill and has great presentation, but I would rather the item cost less than have a fancy box. Overall, this is a great product and can make most server gear into home gear. There isn't much for competition of noctua's 40mm quiet fans, so you kind of have to deal with noctua's high prices if you need a quiet 40mm fan.

This fan replaced a ball bearing fan that was too loud for my application. This noctua fan fits the bill, trading off some cfm for a more enjoyable experienceI have this connected to my car's usb port in the center console to cool down my phone while it's plugged in for apple carplay

I was skeptical when the price of this fan as so much more than others, boy was I glad I still purchased it! The quality of this fan compared to others is unmatched. This fan works off of a 5V pin from a raspberry pi, which most others do not. You can barely tell the fan is on when listening to it it is so quiet. My Pi is in a 3D printed case and without the fan reaches 190C within minutes. With the fan, the pi has not exceeded 110C once over the course of months. I can not rave enough about this fan.

This fan is much less noisy that the stock fan in the Dell Powerconnect switch that it replaced. It does move slightly less volume than the original but it is still plenty of airflow and device temp is unaffected by the swap.My only complaint is price. These are easily 30% higher than they should be. Only time will tell if they are worth the money.

Used to replaced old fan on used network switch. Switch is much quieter now and seems to be running cooler.

These fans are great, I ended up hard wiring these into my server rack ventilation system.

Used this as an internal fan in one of my 3d printers (Bambu P1P). Good fit, easy to install with included wiring harnesses (no soldering required), runs perfectly and quietly.

I bought two of these fans to replace the two loud whooshing, humming Delta Electronics 5V DC Brushless 40x40x10 mm fans on my Netgear GS716Tv1 Smart Ethernet Switch (nice basic web-manageable switch with VLAN, which I picked up for effectively free). With the two replacement Noctua 40x40x20mm fans, the sound level dropped by a factor of 10 to 20 (10-13 dBA) and is now tolerable for office use, with a quiet whirring and white noise from air movement. I used the original screws with the shanked nuts reversed as it was more appropriate than the rubber inserts that came with the fans for this application. I snipped the old fans off their pin connector, and used the wire joining connectors that come with the new fans to adapt the fan's power wires to the original pin connector. It was an easy 25 minute job. Excellent!