The Asus EAH3870X2 differs from the standard ATI partner cards in a few different ways. First and formost is the cooling solution used by Asus. This is a far cry from the hair dryer models of the recent past (think 2900XT and 1900XTX). The cooling solution chosen by Asus uses the same style heatsink on each card instead of the separate copper and aluminum sinks used on the reference ATI design cards. Each heatsink on the Asus EAH3870X2 has a copper base and dual heatpipes leading to the fin assembly to cool down the GPUs. Each heatsink has its own individual fan so that each processor gets it own fresh air. This is in stark contrast to the blow through design used by ATI.

http://www.overclockersclub.com/reviews/asus_eah3870x2/