R680: AMD ATI Radeon HD 3870 X2

Heatsink design

During the briefing with AMD, the company’s representatives talked quite a lot about the heatsink design. With two GPUs on the card, it was important to not only keep both of them cool, but to also achieve this without making the card either too heavy or being anything but quiet with noise more closely resembling a leaf blower.

Noise definitely isn’t an issue, as AMD’s “acoustically enhanced single fan solution” is at least an equal to the Radeon HD 3870 in that respect and it’s definitely much quieter than the reference design Radeon HD 2900 XT for example.

That’s not all that AMD talked about on the heatsink front though, as it claims that it has managed to balance the weight of the card through what it called “enhanced weight management”. Yeah, it sounds crazy, I know... but these are the terms that AMD used in its marketing slides – take them for what they are, in other words.


Basically, what enhanced weight management means is that the company opted for a combination of copper and aluminium to keep the Radeon HD 3870 X2’s GPUs cool. There are a few parts to the heatsink – the main portion is basically the one-piece extruded aluminium design that cools everything except the two GPUs. The GPUs are then cooled by two inserts – the GPU nearest to the fan is cooled by an aluminium heatsink, while the other is cooled by a lump of copper.


Even though it’s easy to get caught up in AMD’s marketing fluff, this does actually make at least some sense. Aluminium is lighter than copper (thus helping to keep the weight of the card down) and it also dissipates heat better than copper. Meanwhile copper is a better conductor of heat, thanks to its higher specific heat capacity, which basically means that it can ‘hold’ more heat than aluminium – this is good because the second GPU is likely to be hotter than the first GPU, as it is cooled second by what is ultimately warmer air straight from the first GPU's heatsink.