However if you opt for a high end air cooler, like the Noctua D-14 or the Thermalright Silver Arrow,or the Thermalright Archon. The Low RPM fans are practically inaudible. They are able to do this as the large 140/160mm fans turn at a speed of 800-1200 RPM and are certainly as quiet or quieter than the radiator fans on a WC system. Additionally the above mentioned coolers are as effective as the top closed loop WC system Corsair (H-100). I run the Silver Arrow with the third fan, and it is simply not audible.