Installation and noise levels
Installing either CPU cooler is a breeze thanks to the detailed instructions on offer as well as the SecuFirm mounting system, which is one of the best available. Install the processor as well as a coating of thermal paste. Then insert the backplate behind the motherboard (most cases usually have a cutout at the back for custom coolers), and ensure that the plate is aligned with the cutouts for the mounting screws.
Tighten the screws and fasten two retention brackets (which secure the cooler) on either side of the CPU. For the cooler itself, ensure that it is aligned with the screw threads of the retention brackets. The last stage is to connect the fan to a fan header or controller on the motherboard. Total installation time should not take more than ten minutes.
Since the coolers are designed to sit low, they do not interfere with memory modules that have a large heatsink, such as Corsair’s Vengeance line. We were able to comfortably slot either cooler next to the RAM module without any clearance issues.
In terms of noise levels, both the NH-D9L and the NH-U9S are barely audible when idling. One of Noctua’s main strengths is in designing CPU coolers that are quiet, and thanks to the newer NF-A9 fan, there was barely any audible sound from the cooler when idling.
Under load, the NH-U9S came in at 41 degrees Celsius, and after running OCCT for over ten minutes, the cooler registered a maximum temperature of 62.5 degrees Celsius. Sound levels never exceeded 42.1 dBA even under full load. Adding a second fan to the mix served to reduce the temperature to another two degrees Celsius while increasing the sound levels by as much as 1.5 to 2 dBA. The NH-D9L is similarly quiet, registering sound levels of a maximum of 41.2 dBA under full load and a temperature maximum of 62 degrees.