360° View - Xigmatek Loki SD963 Heatsink Information on Frostytech's test methodology is available here.
The 134mm tall Xigmatek Loki SD963 heatsink accomodates up to two fans, just one 92mm PWM fan is supplied. Unique to this heatsink are corrugated leading/trailing fin edges. Three 6mm diameter copper heatpipes conduct to the 90mm fin stack above. The 12mm thick aluminum baseplate supports all the heatpipes and mounting brackets.
The 6mm heatpipes extend the full height of the fin stack which is closed off at the sides. Each aluminum fin measures 0.4mm thick and spaced 2mm apart from the next. The bottom fin is elevated 36mm for adequate motherboard component clearance.
Four rubber posts lock into channels in the aluminum fins to support the 92mm PWM fan. Additional channels on the opposite side accommodate a second fan. The leading and trailing edges of the 94x50mm aluminum fins have a corrugated edge pattern. The exposed copper heatpipe base measures 35x48mm in size.

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 base of the Xigmatek SD963 Loki heatsink features exposed heatpipes and is machined perfectly flat in both axis. Surface roughness is at or better than ~8 microinches and both aluminum and copper parts of the base are flush to one another.

Next up, Frostytech heatsink sound level measurements...