Force3D are the latest to equip the HD 4870 with a beefed up cooler, or in this case, a freezer. As detailed here, the "Freezer DHT" lowers temps by 33%.

Force3D are excited to introduce the Force3D Radeon HD4870 with the high performance Freezer DHT cooler that is equipped with DHT (Direct Heatpipe Touch) technology. The heatpipes touch the GPU directly and transfers the heat hence cooling performance is maximized. The fan is silent and its durability is excellent by hydromantic bearing method.