FrostyTech posted a review on the TTIC nPowerTek NPH-K8 Big Heatsink

The (TTIC) nPowerTek NPH-K8 Big heatsink is a huge low noise cooler, but in fact it's that large size which allows it to operate without too much noise. The nPowerTek NPH-K8 Big is a deceptively simple combination of heat column and aluminum fins, intended for a Socket 754/939/940 AMD Athlon64 processor near you. At the heart of this heatsink is a huge copper cylinder; this is the heat column. The heat column is a 33mm diameter hollow copper cylinder which is vacuum sealed, creating the ideal environment for a special chemical coating on the inside that "superconducts heat axially at a molecular level." The technology works on a related concept to traditional heatpipes, but is physically different and should not be confused with the latter.

TTIC nPowerTek NPH-K8 Big Heatsink Review