X-bit labs

The Single-Decker Champ: ATI Radeon HD 3870 X2 Graphics Card Review (page 6)

Category: Video

by Alexey Stepin , Yaroslav Lyssenko, Anton Shilov

[ 02/18/2008 | 10:44 AM ]

Cooling System

Developing a cooler for a dual-chip graphics card is quite a problem but it was solved easily for the Radeon HD 3870 X2. In fact, this cooler consists of two coolers of the Radeon HD 3870 with the addition of a more powerful fan.

There are two individual heatsinks, one for each GPU. The chip that is closer to the fan is cooled with an aluminum heatsink. The more distant chip has a copper heatsink. The Radeon HD 3870 uses a copper heatsink actually, while the GPU frequency of the Radeon HD 3870 X2 is higher and it generates more heat. We guess the developer installed an aluminum heatsink to reduce the overall weight of the card. Each heatsink has a jut at the spot where it has contact with the GPU die. Traditional dark-gray thermal grease ensures proper thermal contact. The heatsinks are not mechanically connected with the base and are fastened to the PCB directly by means of four screws and a spring-loaded back-plate.

The other elements are cooled with the massive red-painted aluminum base. It also carries a fan and a casing made from red translucent plastic. Part of the base is something like a needle heatsink. Two types of thermal pads are used to ensure thermal contact with the memory chips, PCI Express switch and the load-bearing elements of the power circuit: elastic “sandwiches” with a layer of thermal grease between two pink pads, and pads that resemble the ones Nvidia uses on its cards. The cooler’s base is fastened to the PCB with 8 screws separately from the heatsinks. The memory chips on the reverse side of the PCB are cooled with an individual aluminum plate.

This cooling system should cope with its job quite well considering the relatively low heat dissipation of the RV670 chip, yet we’ve got some apprehensions concerning the GPU which is farther from the fan. As for the noise characteristics, you’ll learn them in the next section.