Noctua NF A4x20 PWM, Premium Quiet Fan, 4 Pin (40x20mm, Brown)

Amazon

Premium quiet fan, 40x40x20 mm, 12V, 4-pin PWM, max. 5000 RPM, max. 14.9 dB(A), >150,000 h MTTF Award-winning A-series design with Flow Acceleration Channels and Advanced Acoustic Optimisation frame for superior quiet cooling performance 40x20mm size ideal for 1U servers or replacing fans in network and storage equipment (routers, switches, NAS etc.) or other devices such as DVRs 4-pin PWM version for automatic speed control via 4-pin PWM fan headers, 5000rpm maximum speed (4400rpm with supplied Low-Noise Adaptor) Includes anti-vibration mounts, fan screws, extension cable, y-cable and OmniJoin adaptor set for connecting the fan to proprietary fan headers

123-3D UK

Is your 3D printer, computer or other device making too much noise? This Noctua fan offers the solution: it ensures that your device works whisper-quiet. The aerodynamic fans are popular for their robust, stable and above all quiet character. They ensure optimum airflow. The grooves in the AAO frame allow air to be routed as efficiently as possible for the best cooling results. The integrated shock absorbers and SSO2 bearings reduce the noise level and ensure stability.This fan has a size of 40mm x 40mm x 20mm. The PWM variant has a variable rotation speed. With this fan you benefit from a six-year warranty.