ATI Technologies X1650 manual CrossFire Overview

CrossFire™ Overview 107

1PCI Express® CrossFire™ Compatible Graphics Card

2Radeon® X1650 PRO CrossFire™ Edition Graphics Card

3Partial Frame Rendered on PCI Express® CrossFire™ Compatible Graphics Card

4Partial Frame Rendered on PCI Express® CrossFire™ Edition Graphics Card

5Final Rendered Frame on Display

Some types of textures, especially those with transparent portions, can exhibit aliasing that is not removed by MSAA techniques. Another form of anti-aliasing, known as Super-sample Anti-aliasing (SSAA), can be useful in these cases, because it affects every pixel in an image. Although it normally operates more slowly than MSAA, the power of multiple GPUs can make SSAA practical to use.

SSAA first renders a scene at a higher resolution than that which is output to the display, which is then downsampled to the display’s resolution. This approach normally has two main disadvantages: it requires rendering many more pixels than normal, which can have a drastic impact on performance, and that it results in an ordered grid sample pattern, which does a poor job

of anti-aliasing some types of jagged edges. CrossFire™’s Super Anti- aliasing overcomes both of these problems. It takes advantage of the second GPU to render the additional pixels required for each frame, so there is little or no performance impact. It can also make use of a more effective sample