Summary: I'm surprised at all the 5 star reviews, maybe I got a lemon. Some people talk about "at it's lowest speed". My PC doesn't have speed control, so that's no help. It's supposed to run at 17db, which is pretty quiet. I definitely don't hear it when music is playing, but I can hear it now across the room. I even moved the PC down off of a shelf behind a wooden barrier. All 17 db (at least) are a hum that's about A below middle C.
Summary: I bought this to replace my stock HP fan. It was BOTH louder and blew less air. I REALLY wanted to like this fan but all it did was make me realize my old fan (upon removing it to stick in the Noctua) just needed a little cleaning and after that it ran more air and quiter than the Noctua. So I guess, thank you Noctua in an obtuse way.
Pros: It looks sturdy enough to last forever.
Cons: Unfortunately, you are now DOOMED to a fan that is FOREVER noisy and FOREVER under powered even at full power.
Summary: I've been testing several fans in my case. I'm looking for a good CFM to noise ratio. The best 80 mm fans I've found are the 80mm Nexus fans, which are quieter and push more air than the Noctua. The larger 120mm Thermalright fans are excellent. I got poor results from 80mm Scythe fans.
Pros: Air comes out.
Cons: It has very low air flow (I think the specs are overrated). It is not as silent as other fans with higher CFM. It is more expensive than better fans.
Summary: A comparación de los hermanos mayores de noctua estos ventiladores están por debajo en cuanto a prestaciones. Para conseguir un buen caudal de aire hay que dejarlos a velocidad media/alta produciendo el mismo ruido que cualquier otro ventilador de gama media. No los recomiendo si lo que buscas es silencio.