Coolers are equipped with fans, their speed is controlled by PWM. Model NH-U12DX i4 got one fan NF-F12 size 120 mm, Model NH-U9DX i4 - two 92-mm fans NF-B9.
To reduce noise on the power supply fan can be installed through a step-down adapter. Speed of NF-F12 varies 300-1500 r / min (300-1200 r / min ). Maximum air flow is 93.4 m 3 / h (74.3 m 3/ h during an adapter), the noise level - 22.4 dBA (18 dBA).
Speed of NF-B9 varies 300-1600 r / min (300-1300 r / min ). Maximum air flow is 64.3 m 3 / h (52.6 m 3 / h during an adapter), the noise level - 17.6 dBA (13.1 dBA).
The small size of the radiator NH-U12DX i4, providing easy access to the memory slots. Dimensions without fan are 158 x 125 x 45 mm. With fan, they increase to 158 x 125 x 71 mm. Weight without fan and with a fan of 580 and 755 g, respectively.
Dimensions of NH-U9DX i4 without fans are 125 x 95 x 71 mm. Installation of one fan increases to 125 x 95 x 95 mm, two - up to 125 x 95 x 120 mm.
Price of NH-U9DX i4 is 60 euros, NH-U12DX i4 - 70 euros.