360° View - Noctua NH-L12 Heatsink Information on Frostytech's test methodology is available here.
The top 120mm PWM NF-F12 fans spin at 1500-1200RPM while the bottom 92mm PWM NF-B9 fan spins at 1600-1300RPM. Both fans have separate 4-pin power cables. Looking at the top of the Noctua NH-L12 heatsink with its top fan removed we see two small open squares about half way up the fins stack for the supplied screwdriver to pass through when installing the heatsink. The aluminum fin stack is 128x118mm in size. Both fans are protected from direct contact with the metal fins by small elastomer vibration absorbing pads and cushions.
The Noctua NH-L12 heatsink stands 93mm tall, the bulk of it elevated 48mm over the CPU socket for clearance. The four 6mm diameter copper heat pipes pass through the 128x118mm aluminum fins on a 29mm spacing. Each nickel plated aluminum fin is 0.5mm thick and spaced 1.5mm apart. Note the wire fan clips securing the two fans, the small wire tabs make removing the top 120mm fan or bottom 92mm fan really quite easy.
The nickel plated copper base plate measures 40x38mm in size and 2-4.5mm thick. The four 6mm diameter copper heatpipes are soldered to the copper base plate and aluminum fins along their entire length for good thermal conductivity. Since the total weight of the aluminum fins are supported by relatively fragile heatpipes, be careful not to bend things when installing this cooler.

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.