360° View - Noctua NH-U9S Heatsink Information on Frostytech's test methodology is available here.
The NH-U9S heatsink stands 125mm tall and is fitted with a 92x92x25mm NF-A9 PWM fan that rotates at 2000RPM. Power is supplied by a standard 4-pin mobo header. A second fan can be attached, increasing the NH-U9S footprint from 95x95mm to 95x122mm. The nickel plated aluminum fins measure 0.4m thick and are spaced 1.75mm apart. Heatpipes are roughly spaced apart 57mm on center.
The Noctua NH-U9S utilizes an 87mm tall stack of nickel plated aluminum fins soldered to five 6mm diameter copper heat pipes. The lowest cooling fin is elevated 32mm for motherboard clearance. The copper heat spreader of the base measures 3.7mm thick. Wire fan clips have low-profile thumb tabs which make fan removal easy.
The base of the Noctua NH-U9S heatsink is fabricated from a solid block of copper which is nickel plated. All five copper heatpipes are soldered to the center of this baseplate. The base has a machined surface finish and measures 38x40mm. Looking at the top of the NH-U9S heatsink we can see the tips of the five 6mm diameter U-shaped copper heatpipes. Each aluminum fin is 86 x 66mm in size. Fans can be mounted on both sides, if desired.

Base Finish and Flatness

Flipping a heatsink over to inspect the business end is often a simple indicator of overall cooler quality. More practically speaking, a heatsink is in many ways only as effective as the contact it makes with the processor - the flatter and smoother the better. Base finish is one of the criteria that Frostytech measure in the course of evaluating heatsinks, and it involves two distinct aspects. Surface Finish is the first; this is calculated with the aid of Surface Roughness Comparator that has a cross section of common machine surface finishes and their numerical surface roughness equivalents in microinches. The second is Surface Flatness. This is tested with an engineer's straight edge or proven flat surface, in two axes.

The Noctua NH-U9S heatsink uses a nickel-plated copper base plate which is machined very smooth, surface roughness is at or better than ~8 microinches. The base is very slightly concave in the axis parallel to the heatpipes, very slightly convex in the opposite axis.

Sound level measurements are coming up next on Frostytech...