360° View - Glacialtech Igloo 5610 Plus Silent Heatsink Information on Frostytech's test methodology is available here.
The twin 92mm fans on Glacialtech's Igloo 5610 Plus Silent heatsink each rotate at 1200RPM by default. Power is supplied by one 3-pin motherboard fan header. The Igloo 5610 Plus Silent heatsink stands 139mm tall, 94mm wide. Two 6mm diameter copper heatpipes are used to conduct heat energy from the base to the 91mm tall section of raw aluminum cooling fins above.
Each aluminum fin on the Igloo 5610 Plus Silent heatsink is 0.3mm thick and spaced 1.5mm apart. There is no plenum behind the fan per say, but the scalloped edge on the fins likely has a similar effect. Clearance below the lowest fin is 35mm to the CPU.
Two 6mm diameter copper heatpipes pass through the aluminum fins. At the base the heatpipes are packed 5mm apart, flattened slightly and soldered to the 1mm thick copper base plate. The base measures 32.5x34mm in size and ships with a pre-applied patch of thermal compound.

Next up Frostytech measures the sound output from the Glacialtech Igloo 5610 Plus Silent heatsink with its fan running at full speed...