From this point forward, we'll be comparing the performance of the Diamond Viper Radeon HD 2900 XT 1GB to its competition in dual-card, CrossFire and SLI configurations.
Performance Comparisons with 3DMark06 v1.0.2
3DMark06 is the most recent addition to the 3DMark franchise. This version differs from 3Dmark05 in a number of ways, and includes not only Shader Model 2.0 tests, but Shader Model 3.0 and HDR tests as well. Some of the assets from 3DMark05 have been re-used, but the scenes are now rendered with much more geometric detail and the shader complexity is vastly increased as well. Max shader length in 3DMark05 was 96 instructions, while 3DMark06 ups that number to 512. 3DMark06 also employs much more lighting and there is extensive use of soft shadows. With 3DMark06, Futuremark has also updated how the final score is tabulated. In this latest version of the benchmark, SM 2.0 and HDR / SM3.0 tests are weighted and the CPU score is factored into the final tally as well.
Just like we saw in the single card tests, the dual card Viper Radeon HD 2900 XT 1GB CrossFire configuration put up an overall 3DMark06 score just slightly lower than its 512MB counterpart.
This time around, however, the Viper Radeon HD 2900 XT 1GB CrossFire rig finished behind the 512MB Radeon HD 2900 XT CrossFire configuration in both the Shader Model 2.0 and Shader Model 3.0 / HDR tests. At these settings, 3DMark06 is limited by the GPU's shader performance and fillrate, and not so much by its frame buffer size and memory bandwidth.