SuperAA/Platforms

One new feature ATI has implemented into CrossFire is what they call “Super anti-aliasing”. This refers to two abilities which are unique to Crossfire. The first is CrossFire’s ability to mix sampling patterns from both cards, providing sharper visuals, and the second is CrossFire’s support for higher AA modes than previous ATI offerings. As a result of these features, Super AA provides even more optimal sampling patterns and more samples per pixel than previous AA implementations. We’ll start with the enhanced sample patterns first.

In order to improve AA quality, each CrossFire board uses slightly different rotated-grid sampling patterns, proving excellent load balancing. ATI’s compositing engine chip then takes the different sample patterns from the two boards and blends them together to produce the final image. This results in an even better looking final image.

Higher AA modes

In addition to the standard 2, 4, and 6 sample AA modes ATI has provided previously, for CrossFire, ATI also adds 8x, 10x, 12x, and 14x modes for even better-looking visuals.

In the case of CrossFire’s 8xAA mode, both cards are running in 4xAA mode, for an effective equivalent of 8xAA (at 12xAA, both cards are running in 6x mode). The 10x and 14x modes mix multisampling with supersampling for even better image quality. At the 10x setting for example, the cards mix 8x multisampling with 2x supersampling, while 14x combines 12x multisampling with 2x supersampling.

Chipsets

On the chipset side, ATI is providing CrossFire solutions for both Intel and AMD platforms. Both chipsets build largely on ATI’s XPRESS 200 chipset, which was launched by ATI several months ago, the key additions are support for newer technologies such as DDR2-667 on the Intel platform as well as 1066MHz FSB, while the AMD platform supports newer storage technologies natively such as 300MB/sec SATA with NCQ support (provided externally), SMP, and CAS latencies as low as 1.5 on the memory.

Both chipsets are built on a 0.13-micron manufacturing process, so they require no active cooling for operation. ATI even integrates 4-phase power circuitry on their reference AMD board for even greater levels of overclocking, while the Intel platform is offered solely with integrated graphics (ATI has no immediate plans for an IGP CrossFire AMD-based board). ATI is also quick to point out that their CrossFire solution doesn’t require a selector card or jumpers, unlike NVIDIA SLI.