360° View - Dynatron G556 2U Server Heatsink Information on Frostytech's test methodology is available here.
The 20x77x77mm PWM fan spins at 5500RPM and draws power from a standard 4-pin motherboard header. Air is exhausted down into tightly pitched aluminum fins. The aluminum fins are 0.4mm thick and spaced~1.0mm apart.
The aluminum fins stand 37mm tall, approximately 27mm of which is exposed for exhaust air to escape. The copper heat spreader is 4-6.5mm thick. Note the captive, spring tensioned screws for installation onto socket LGA1366 Intel Xeon processors.
Four 6mm diameter copper heatpipes are embedded into the copper base plate of Dynatron's G556 2U server heatsink at the center, directly over the CPU mounting pad. The patch of pre-applied thermal compound is 35x35mm in area.

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 copper base of the Dynatron's G556 heatsink has a machined surface finish which is perfectly flat in both axes. A minimal machining texture is left in the copper, giving it a surface roughness of approximately ~32 microinches.

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