NoctuaNF-A4x20 PWM, Premium Quiet Fan, 4-Pin (40x20mm, Brown)

I recently added the Noctua NF-A4x20 PWM to my server setup, and the performance of this 40x20mm fan has left me thoroughly impressed. Noctua's reputation for premium quality is well-deserved, and this fan is no exception.Firstly, the build quality is exceptional. The brown color may be unconventional, but it's a symbol of Noctua's commitment to quality. The construction feels robust, and the attention to detail is evident. This fan exudes durability, assuring me that it can handle continuous operation in a server environment.Now, let's talk about the noise level—or rather, the lack of it. This fan is remarkably quiet, especially considering its size. Noctua's focus on providing a quiet solution without sacrificing performance is evident here. Whether my server is working at full capacity or idling, the NF-A4x20 PWM operates silently, contributing to a peaceful and distraction-free environment.The PWM functionality is a standout feature. The fan's speed is dynamically controlled based on the system's temperature needs, ensuring optimal cooling without unnecessary noise. This adaptability is a game-changer for maintaining the right balance between temperature control and acoustics.Installation was a breeze, thanks to the included accessories and clear instructions. The fan integrates seamlessly into my server setup, and the 4-pin connector allows for precise control over its operation.The performance, reliability, and quiet operation make it a top-tier choice for anyone seeking a compact, high-quality fan for their server. In my book, it's a solid 5-star product, and I wouldn't hesitate to recommend it to anyone looking to add performance and lower the noise level of their server or PC.

I purchased this item to replace the stock cooling fan in my MikroTik CRS310. As always, the included Noctua accessories and cables are ridiculously high quality. After installing the Noctua, I have enjoyed near silent operation and have had 0 issues with cooling. I have recommended this to many people.

Excellent and very quiet fans! I bought a rackmount network switch that arrived with typical server room fans. You know the kind. They sounded like a jet engine when idling and you're afraid that the switch will fall off the shelf from their propulsion. While I'm sure the air pressure, air volume, and airspeed were all higher, this Noctua 40mm fan is no slouch either. There's plenty of air pressure and airflow to keep it running at normal temperatures in my bedroom closet. Even at top speed, this fan is adequately quiet. I'm sure it'd be inadequate in a big data center, but I don't have one of those (and wouldn't want to pay the power bill if I did).

I don't write reviews here often, but this device really warranted it. We have an NVR for our security system and lately the fans just seemed to louder than usual. I did some research through YouTube and several mentioned replacing the fans for the unit we have and recommended these fans. I was a bit skeptical thinking would it really make that much of a difference and is this something I should even mess with.I decided to give it a try and all I can say is I wish I would have done this sooner. It was quite easy to remove the existing fans and the the new fans are all wired and come with their screws (the original screws were too small). I did have to shave a little plastic off the connector as it is too narrow for the existing. But just a blade from a box cutter did the trick. I connected them, screwed then in place and put the device back together. As soon as I powered up the device... I convinced they were not even working because it was completely silent. I used a flashlight and sure enough, the fans were turning. But they are insanely quiet! It's sad the equipment I purchased doesn't use a quality quiet fan such as this product. I cannot recommend these enough. Super easy to replace and just incredibly quiet.

Works well, fits right into the spot the old 40x40x20 mm fan went. That thing was noisy as heck on start up. Board inside the TEG-S708 has 3-pin fan port, so voltage line controls rpm, but this 4-pin from Noctua works just fine in the 3-pin port. Fan still changes rpm speed based on voltage line. Silent as heck. It does move less air than stock, but still enough air over the 10G switch heat sinks to cool it down. Laser readings on heat sinks were under 44C after couple hours of power on.

My NerdAxe miner went from “too loud to have a zoom call nearby” with the old fan, to “I can’t tell if it is on without looking at the screen” quiet with this fan. Besides wonderfully quiet, it speed modulates properly, is nice to look at, and came with accessories for all sorts of mounting/power scenarios. So while not inexpensive, it was worth it!

Why did you pick this product vs others?:Got this to Modify the Polymaker Polydryer which was loud!!!! With this fan, as expected, is super quiet. Perfect mod.

Great fans, but absolutely revolting color scheme. I managed to dye these almost completely black using RIT Dye More synthetic dye graphite color (the regular RIT dyes did not work for me). Used the whole bottle of dye and just enough boiling water to keep the fans I was dying covered, kept at almost boiling for an hour, washed them with clean water, and then dried them over night. Fans still work great, but they still have a very slight hint of brown color. I may try again using a the synthetic blue or just more dye to make them darker, but unless you look at them under bright light you would say they are black. Noctua I will pay a few $ more if you just make these in black so that I don't have to make a mess with dye.