ATI's app-specific optimizations debut
In the wake of the Radeon X700's launch, some of you may have missed the news that ATI will be including application-specific optimizations in future revisions of its Catalyst drivers, including the ones we used for our X700 testing. I see there are a number of new articles kicking around out there today about this development, so I thought I'd point you to our coverage, as well. The first thing you need to do is read our article about a problem with Doom 3 texture filtering, in which we first reported that ATI would be incorporating app-specific optimizations. Next, go to this page of our Radeon X700 review to learn more about Catalyst A.I., including specific details about ATI's approach to optimizations and which games will be initially affected. We also have a quick write-up on Catalyst Control Center, ATI's new-look control panel for the Radeon series, which I think needs some additional work.
Once you understand what Catalyst A.I. is all about, hit this page of the review for DOOM 3 performance results on the X700 XT with and without Catalyst A.I. enabled. You'll see that ATI's optimizations make a big difference in performance. The scores on that page with the Catalyst 4.10 beta drivers are also directly comparable to the Cat 4.9 scores (without Catalyst A.I.) in our GeForce 6600 GT review. You'll notice that the Radeon X600 XT, 9800 XT, and X800 Pro also benefit greatly from the optimizations in the 4.10 beta drivers. For instance, the Radeon 9800 XT's score at 1024x768 jumps from 59.2 frames per second to 70.6. The primary reason for the performance increase, I believe, is a shader replacement that substitutes math operations in place of a texture value lookup for specular lighting, very similar to the famous hack at B3D. Doing the math is faster than accessing the texture on ATI's newer hardware, so the game runs faster. This is one way Cat A.I. can help ATI cope with the fact that's Doom 3's primary code path seems to be less than optimal for ATI hardware.
Catalyst A.I. also allows one to disable ATI's adaptive texture filtering, and we've demonstrated the mathematical differences between the adaptive and traditional approaches to texture filtering by subtracting one of our sample images from another for the benefit of you graphics eggheads out there.