Review on 🌀 Noctua Premium Quiet Fan, NF-A4x10 PWM, 4-Pin (40x10mm, Brown) by Chris Barreto

I bought this to cool the LSI 9207-8i (https://www.amazon.com/dp/B0085FT2JC) host bus adapter and it seems to be fine function. This fan spins at just under 5cfm (at top speed) with a noise level of just under 20dB, which seems pretty typical. PWM means it can be plugged into a PWM fan header to control its speed for even less noise, although it's barely audible from a few feet away, even at full throttle. It also comes with a variety of accessories, including a PWM-capable Y-adapter that lets you connect 2 fans (more if you use chain adapters) to a single header. Overall I think this is a good choice for a 40mm silent fan. (I believe the Noctua A4x20 is sturdy too, but it seems to increase airflow a bit and double the height with a wider "deadzone" in the middle, which for my use - the direct-to-heatsink-mounted fan - wasn't ideal.)