360° View - Xigmatek Gaia SD1283 Heatsink Information on Frostytech's test methodology is available here.
The 120mm PWM fan spins at 1500-80RPM and draws power from a standard 4-pin PWM motherboard fan header. It is backwards compatible with 3-pin connectors. Each of the three copper heatpipes are 8mm in diameter and extend from the base up to the top of the 159mm tall heatsink. Each aluminum fin measures 0.4mm thick and are spaced 2.0mm apart.
The Xigmatek SD1283 Gaia heatsink stands 159mm tall, the tower is 50mm wide (w/o fan) and the first fin is elevated 36mm above the CPU socket. Heat pipes are positioned 11mm on center at the base plate and rise up 72mm apart. The base incorporates a 14mm thick aluminum section to provide support for clamping. Notice the closed notch along the side of the SD1283 Gaia's tower, this curved bend in the edge of each aluminum fin creates a duct to direct airflow towards the region pierced by the three 8mm diameter heatpipes. A fold in each fin works together to create a center channel 40mm wide.
The usable area of the Xigmatek SD1283 Gaia's base is 35x40mm in size. Looking from the top down we see a large v-shape notch on both sides of the fin tower, located directly behind the fan motor. This area typically sees little airflow so it tends to be opened up on modern heatsinks. The fan plenum ranges from 5-17mm as a result. Heatpipes are positioned in the path of highest airflow and rubber mounts are used to hold the fan in place - which means only 120mm fans can be used.

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.

Most exposed heatpipe base heatsinks are machined flat, what you really need to look carefully for is uneven aluminum-copper-aluminum-copper.... joints. Some heatsinks fail in this crucial area because the manufacturer doesn't have the necessary skill to swage the heatpipes into the aluminum support base in such a way that they wont shift. In this case, everything looks good with the Xigmatek SD1283 Gaia heatsink.

The surface roughness of the base is approximately 16 microinches, which is considered excellent. The base finish is smooth/machined and is flat in both axis. There are six small voids created along the sides of the heatpipes, but these serve a positive use when the heatsink is clamped down. The channels enable excess thermal compound to squeeze out from between the heatsink and processor.

Next up, Frostytech heatsink sound level measurements...