360° View - Noctua NH-U12S Heatsink Information on Frostytech's test methodology is available here.
The 120x120x25mm PWM fan spins at 1500RPM and draws power from a standard 4-pin motherboard header. The aluminum cooling tower measures 107x116x45mm in volume. The five heatpipes are grouped towards the sides to conduct heat directly to regions which receive the highest airflow from the fan. A portion of the leading and trailing edges of the fins have a saw-toothed profile.
The Noctua NH-U12S heatsink stands 158mm tall, with the bulk of it elevated 41.5mm for clearance of adjacent memory slots and VRM heatsinks. The five 6mm diameter copper heat pipes expand from side-by-side to 60mm spacing as they pass through the fins in a staggered arrangement. Each nickel plated aluminum fin measures 0.4mm thick and is spaced 2.0mm from the next. Note the wire fan clips used to secure the fan to the fin stack and the brown rubber insulating pads which cut down on vibrational noise.
The base of Noctua's NH-U12S heatsink measures 40x38mm in size. The copper base plate is 2mm to 4.5mm thick. The five 6mm diameter copper heatpipes have been soldered to the copper base plate and to the aluminum fins as well.

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 base of the Noctua NH-U12S heatsink is the gold standard in how heatsinks should be finished. The nickel plated copper base has a surface roughness of approximately ~16 microinches and is perfectly flat in both axes.

Next up, let's see how this heatsink handles the heat compared to a selection of other heatsinks!