Bought for implantation in a box or height CHDW limité.Par rest against the original fan was advantageously replaced by two others of the same make limited in speed; 2x NF-B9 PWM 1600 redux ... To keep a minimum sound level and keep a large air flow to cool my i7-4790K, and it works on top never more than 73 ° to + use extreme - 1200 Tr / min. In addition thanks to the PWM speeds are continually adjusted and rarely conducted maximum.Merci NOCTUA and Amazon Prime.