We start with thermal testing to compare AMD's reference Radeon HD 7970 to Arctic's Accelero Xtreme III with EKWB's copper shim, Arctic's Accelero Xtreme 7970, and Deepcool's Dracula 7970.
The Dracula 7970 and Accelero Xtreme 7970 perform almost identically, posting excellent sub-60-degree results under load. When you consider the reference cooler approaches 80 degrees, the improvement is quite impressive.
As we might have expected, adding a shim between the heat sink and GPU takes a toll on efficiency, yielding a mere eight-degree improvement over AMD's vapor chamber, and trailing the Accelero Xtreme 7970 by 14 degrees.
All of the aftermarket coolers generate comparable acoustic results. This is something we would expect from the Dracula, since its power source doesn't change (hence, there is no fan ramp). Nevertheless, the three models perform well enough to shine a spotlight on the reference design's weakness: noise.
In contrast, we would have thought that Artic's cooler would have demonstrated more variable measurements. We are able to force a 100% duty cycle using AMD's driver, and we know it's possible to spin the Accelero's fans up because we can hear the difference. Thus, we can conclude that the fan profile on the Radeon HD 7970 doesn't impose significantly higher fan speeds until the GPU temperature rises above 68 degrees.