Noiseblocker NB-BlackSilentFan XM1 40mmx10mm Ultra Silent Fan - 2800 RPM - 9.2 dBA

I use tons of quad 2.5" hot swap enclosures and they all come with a very noisy 40mm fan on the back. I can't just take the fan off because I need at least a little airflow due to the density, so instead I splurged and bought a bunch of these super-quiet fans to replace the stock fans in the enclosures.I give them an A+. I get enough airflow for my needs and they are just super-quiet. The only issue is that they do have a fairly high startup resistance so if you have a fan control switch (e.g. LOW and HIGH), you have to set it to HIGH or the fan might not start at boot. Which is fine, I don't even hear the fan.-Matt

These are extremely quiet fans, but just be aware they don't move a lot of air. That said, they seem to be perfect for my raspberry pi, and probably other small electronics that don't need a lot of cooling. No more hi temp warnings on my octoprint setup after I installed one of these.

I've tried this to replace my ender 3 pro hot end fan, which was super noisy. It is much quieter (practically silent), but the airflow is horrible, my temps went up drastically. I used Noctua 10mm x 40 mm instead and airflow is much better.

Decided to get these to incorporate into my build to keep the noise level to a minimum. I needed small fans for a tight spot and my current 40mm fans were strong but way too loud. After setting two of these on full speed, It was nearly silent, but also nearly no airflow. I'd recommend these if you just need low airflow in a tight space.

Super quiet. Was satisfied with the noise levels so I bought 2. They both failed after a year apart. If you are going to use them in something that runs 24/7, please consider this before you buy. Might want to consider noctua and give you them a shot instead of saving a buck. Fan failure is sudden and once in a while you will hear a loud chatter when the bearings finally start to let go. However, it was super quiet until they failed.

I am using these in my 3D printer. They move the air and I cannot hear them at all. After swapping out the stock fans for these my printer got so quiet I thought it may be hunting wabbits.

Installed on a makerbot replicator 2. Very quiet, can’t even tell it’s on! Pushes much more air than stock fans and the blue color is a nice touch. Had to splice wires to get it connected, but was very easy.

QUIET. Installed on an Anet A8 3D printer, cant even tell the fan is on its so quiet. Very happy. Did have to solder the cables to the old fan cable, but that was easy and i knew that before ordering.