The 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 20cm 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.Award-winning Noctua quality in 20cm sizeWhile more and more PC cases support 20cm intake, side-panel or exhaust fans, many of the bundled stock units and available aftermarket options are of questionable quality. By contrast, the NF-A20 is a true premium grade solution worthy of Noctua’s award-winning A-series.154mm, 110x180mm and 170mm hole spacingIn order to ensure broad compatibility with today’s PC cases, the NF-A20 features three sets of mounting holes: While the 154x154mm and 110x180mm spacing allow it to replace most 200mm fans, the 170x170mm spacing is used by many 230 and 250mm fans, which can thus also be replaced by the NF-A20.ATTENTION: As there is no fixed industry standard for the size or hole spacing of 200mm, 220mm, 230mm or 250mm fans, please carefully check both the hole setup of your chassis and the available space (the NF-A20 is 30mm thick whereas some other 200mm fans are only 20mm!) in order to verify that the NF-A20 is compatible with your chassis. In case of doubt, please contact your chassis manufacturer.