The cooling system of the Radeon HD 5870 is a time-tested, simple and clever solution that has been used by both GPU developers for a long while. In other words, it is a rather large aluminum heatsink connected with heat pipes to a copper base that contacts with the GPU die. There are four heat pipes here which should ensure uniform distribution of heat.
As usual, the aluminum frame the heatsink and fan are installed on takes heat off the memory chips and power transistors of the voltage regulator. Elastic pads ensure proper thermal contact and a layer of traditional dark-gray thermal grease is used for the GPU. The heatsink is cooled by a blower with red impeller that becomes very loud at increased speed.
The photo shows the air duct for some of the airflow to move at an angle of 90 degrees to the mounting bracket.
Thus, only part of the hot air leaves the cooling system in the ordinary way. The other part is blown into the system case through the slits in the cooler casing:
This is an unavoidable compromise because the Radeon HD 5870’s mounting bracket is populated more densely than those of previous-generation Radeon HD cards and does not have much place for vent holes.
The whole contraption is fastened to the PCB with a few screws. An X-shaped back-plate ensures proper contact between the GPU die and the cooler’s heat-exchanger. As we’ve mentioned above, the metallic plate that covers the back of the PCB is a purely decorative element and has no practical function. There is nothing to cool there.
Summing it up, there are no special innovations in the design of the cooling system installed on the Radeon HD 5870. It is a rather simple and long-known design that has repeatedly proved its worth in real applications. The question is how hot the RV870 is going to be. Even though manufactured on 40nm tech process, it consists of over 2 billion transistors. Doesn’t the cooler get too loud maintaining a safe GPU temperature? We’ll check this out in the next section.