360° View - Noctua NH-D14 Heatsink Information on Frostytech's test methodology is available here.
The left-most fan is a 120x25mm NF-P12 that spins at 900-1300RPM. The middle fan is a NF-P14 that operates at 900-1200RPM and measures 140mm. Two standard 3-pin motherboard headers provide power. Looking at the top of the Noctua NH-D14 heatsink we two separate towers 140x50mm in size, each stands 106mm tall. The six heatpipes thread through the widely spaced fins and are soldered in place to lower thermal joint resistance. Fin edges are given a saw-toothed profile.
The Noctua NH-D14 heatsink stands 161mm tall, but the bulk of it is elevated 45mm for clearance of adjacent board mounted devices. The six 6mm diameter copper heat pipes expand from side-by-side to a ~11mm spacing as they pass through the fins. 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 two fans in position on the NH-D14.
The base of Noctua's NH-D14 heatsink measures 40x38mm in size. The copper base plate is 2mm to 4.5mm thick. The six 6mm diameter copper heatpipes have been soldered to copper base plates, 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 engineers straight edge or proven flat surface, in two axis.

The Noctua NH-D14 heatsink has a machined nickel-plated copper base with a surface roughness of approximately ~16 microinches, which is considered very good. The base plate is machined flat in both axis. One aspect of the Noctua NH-D14's design you've probably noticed is that the six heatpipes are soldered to a 2mm thick copper base plate rather than flattened and exposed heatpipes. Noctua have indicated that a heatspreader is generally better for cooling processors which may have localized hot spots, according to their own in-house tests.

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