Performance recapAlthough individual game results are obviously worth looking at when you want to gauge performance in a specific game, we have also calculated a performance index based on all tests with the same weight for each game. The results for Batman Arkham City with GPU PhysX, Crysis 2 with tessellation and Project Cars haven’t been taken into account for the index.
We set an index of 100 to the Radeon HD 6970 at 1920x1080:
Hold the mouse over the graph to classify the cards by performance at 1920x1080.
The Radeon HD 7970 gives an average gain of 36 to 43% over the Radeon HD 6970, depending on the resolution. The gain over the GeForce GTX 580 is 22% at 1920x1080 and 31% at 2560x1600.
This isn’t enough to overtake the GeForce GTX 590 and the Radeon HD 6990, nor the mid-range multi-GPU systems: the Radeon HD 6870s and GeForce GTX 560 Tis. These solutions only have a slight advantage over the 7970 however and as far as we’re concerned don’t therefore justify all the outlay for a multi-GPU system. Moreover, they suffer slowdowns in certain games as their 1 GB memory is insufficient.
The Radeon HD 7970s in CrossFire X are at the head of the field as might be expected, even though they’re affected by a significant CPU limitation in F1 2011 and by a non-functioning CrossFire X profile for Batman Arkham City.
During all these tests we noted a tendency with the Radeons: they tend to suffer more than the GeForces when the deferred rendering engines use MSAA. It’s a complex task to use this type of antialiasing in a deferred rendering engine. There’s an example in our report: Understanding 3D rendering step by step with 3DMark 11
. Although we can’t see any technical reasons for this, we imagine that AMD has reduced its optimisation efforts, preferring to highlight the antialiasing carried out during post processing, such as FXAA or MLAA, which is simpler to support.