Nexus launched NHP-2200, a northbridge heatsink fully constructed out of copper. By using almost pure copper material Nexus managed to squeeze out the best possible performance.
Heatsink is made of copper and has 143 mm long U-type heat pipe. Size of this cooler is 46x46x63.3mm and it weights 114.5 gram. Nexus claims it can be mounted on all major chipsets. Since it is a passive heatsink it produces zero dB, so no noise at all. Nexus supplies thermal grease with this heatsink.
You can find more information on Nexus.