Anti-Aliasing Performance Scale
Due to the total number of anti-aliasing modes now offered by ATI with the X1000 graphics family, it would be a monumental undertaking to do an as close to apples-to-apples comparison of all of the AA modes available on both NVIDIA's and ATI's platforms. We know you'll be interested in how each successive level of standard anti-aliasing and adaptive AA perform, however, so we ran one of our custom benchmarks in every mode offered with ATI's current drivers to give you an idea as to how these new modes affect performance.
Using our custom FarCry benchmark, with the game patched to v1.33, we ran the game at two resolutions with an increasing level of anti-aliasing applied. As expected, performance dropped as more and more pixel processing was being performed on the scene. With FarCry in particular, we'd say playability begins to suffer once you enable 4x Adaptive AA. 6x Adaptive AA was a bit to much for the X1800 XT to handle with a game like FarCry though. With older titles, or CPU bound games, however, the higher levels of Adaptive AA should be perfectly playable at relatively high resolutions, and they'll offer superior image quality than was available with ATI's previous generation of cards.