Scythe NCU-2000 Pentium4 Heatsink Review
"The Scythe NCU-2000 is a revised version of the TS Heatronics NCU-1000 fanless heatsink, offering up compatibility with the Socket 754/939 Athlon64 processors as well as the good old Pentium 4 CPU. What makes the NCU-2000 unique is that it is an entirely passive cooling solution. It functions by making use of the air currents that exist within a computer case to keep itself, and the processor cool. While the Scythe NCU-2000 is technically a 'zero noise' heatsink, it cannot operate without some degree of air flowing over its fins."