Noctua"s NF-P14 fan has become a default-choice among PC enthusiasts looking for a premium quality quiet 140mm fan. NF-A14 provides higher static pressure and an even better airflow/noise ratio than its much acclaimed predecessor. * The NF-A14"s square 140mm frame with 140mm mounting holes makes it a premium grade replacement for common 140mm case fans & perfect for use on 140mm water cooling radiators, where its square shape will ensure full coverage & best pressure performance. * The NF-A14 impeller features suction side Flow Acceleration Channels. By speeding up the airflow at the crucial outer blade regions, this measure reduces suction side flow separation and thus leads to better efficiency and lower vortex noise. * Noctua"s AAO (Advanced Acoustic Optimization) frames feature integrated anti-vibration pads as well as Noctua"s proprietary Stepped Inlet Design and Inner Surface Microstructures, both of which further refine the fan"s performance/noise efficiency. * Noctua"s Stepped Inlet Design adds turbulence to the influx to facilitate the transition for laminar flow to turbulent flow, that reduces tonal intake noise, improves flow attachment, incur suction capacity, especially in space restricted environments. * Integrated Anti-Vibration Pads made from extra-soft silicone minimize the transmission of minute vibrations while maintaining full compatibility with all standard screws and other mounting systems. * Providing 800 and 650 rpm speed settings via the supplied adaptor, the ULN (Ultra-Low-Noise) version is tailor made for serious silent enthusiasts who demand super-slow running speeds and utmost quietness of operation. * The latest version of Noctua"s advanced Smooth Commutation Drive system ensures superb running smoothness by eliminating torque variations and switching noises. This makes the NF-A14 remarkably quiet even at very close distance.