Noctua NF-A20 PWM 200mm x 30mm PWM 4-pin Fan\n\nThe NF-A20 is a highly optimised; premium quality quiet 200mm fan. Featuring an AAO (Advanced Acoustic Optimisation) standard frame as well as sophisticated aerodynamic design measures such as Flow Acceleration Channels; the NF-A20 brings the renowned quiet cooling performance of Noctua's award-winning A-series to the increasingly popular 200mm form factor. The PWM version uses Noctua's custom designed NE-FD1 IC for fully automatic speed control via 4-pin fan headers; which allows it to strike a perfect balance between quietness and ventilation performance in each given situation. Its superb running smoothness; reference-class SSO2 bearing and Noctua's trusted premium quality make the NF-A20 an elite choice for the highest demands.\n\n Award-winning Noctua quality in 200mm size While more and more PC cases support 200mm intake; side-panel or exhaust fans; many of the bundled stock units and available aftermarket options are of questiona;