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

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.

Used to correct an issue with a Cisco switch where the engineers install fans that sound like nails on a chalkboard in a world where Noctua exists.

This product has what I would say the best packaging and labeling I have ever seen. Good god, if only everything was this good. I ordered these fans for a ubiquiti UNVR which had erratic fan howling (fans going at different speeds making a very weird low hum, too loud for an office). I installed these Noctua fans and fan operation is now silent. Thank you to this company.

Quiet and works just right

Fast shipping, these are nice little fans for servers so quiet and makes my office nice to be in.

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.

Great upgrade to make my Mikrotik Router quieter.

It's quiet, which I like, and it comes with super thoughtful accessories. Those things are carrying the weight of my 4 stars, because the big issue is that the fan doesn't move much air. Not nearly as much as a typical "thick" 40mm fan. I just don't know what the application is. If you try to replace a screaming server style fan, these will not come close to moving enough air. Maybe this is good if you have space and want to replace a loud 40x10 fan?