ATI Crossfire Video Card Review :: X1K Series Features

Microsoft first introduced the DirectX API with the introduction of the Windows Operating system. A new DirectX has been released every year or two, with the last major release being DirectX 9.0 in 2002. Microsoft was forward thinking with DirectX 9.0 having both Shader Model 2.0 and 3.0 in the same DirectX. Pixel Shader 3.0 and Vertex Shader 3.0 are important for video cards released today as virtually every video card sold today support them, with the exception of the odd X800 series card.

I've covered the primary features of the X1900 series with my various X1800XT reviews. The X1900 shares the same feature-set, with the exception of the tripled ALUs. Pixel Shader 3.0 allows nearly unlimited pixel Shader instruction lengths, has a back-face register for two-sided lighting supports dynamic branching, and more. Almost every game released today uses Pixel Shaders in them somewhere. F.E.A.R., for example uses Shaders in the textures, in the lighting, in the fog and more. Vertex Shader 3.0 is similar in that it allows nearly unlimited Shader length programs, render to vertex buffer and more.

A big feature that was introduced with the GeForce 6800 series was HDR Lighting or High Dynamic Range Lighting. A major problem with pre-DX9 hardware was the inability of the hardware to do contrast ratios of more than 8-bits per color component. DX9 hardware introduced floating-point color calculations, allowing a wider range of color contrasts to be viewable in a game. The High Dynamic Range on the X1900XTX is based on Floating Point 16-bit blending, allowing for up to a contrast ratio of 65,536:1 versus the Integer based DX8 hardware with a 255:1 ratio. HDR offers a lot to game developers looking to get just a little better lighting dynamics in their game.

As a big image quality freak, improved Anti-Aliasing is important to me. It's disappointing that NVIDIA and ATI haven't improved their single card AA in years. Multiple video cards allowed them to improve AA. Crossfire allows the card to increase the samples from 6X to 8X (4X+4X), 10X (4X+4X+2X SSAA), 12X (6X+6X) and 14X (6X+6X+2X SSAA).

ATI's Crossfire has 3 modes of operation: AFR (Alternate Frame Rendering), Scissors (Split Frame Rendering) and SuperTiling. AFR has each graphics card render a frame one after the other. Scissors has the two video cards working together on a single frame. SuperTiling mode has each graphics card render alternating tiles of a screen. The compositing chip combines the tiles into a single frame.

One of the issues I had with early ATI cards was the lack of frequent updates and stability issues. With the hiring of Terry Makedon, ATI made a conscious effort to improve their drivers. Today ATI drivers are solid gold, with monthly releases meaning even if a problem arises the fix is fast. ATI has already released 3 Catalyst drivers this year.

Drivers