XFX 7600GS XT SLI Video Card Review :: The XFX 7600GS XT Features

• 90 nanometer low-k dialectic process
• 178 million transistors
• 12 Pixel Shader pipelines
• 5 Vertex Shader pipelines
• 500MHz core clock
• 450MHz memory clock (900MHz Effective)
• DirectX 9.0c
• Pixel Shader 3.0
• Vertex Shader 3.0
• HDR
• Vertex Texturing
• SLI
• SLIAA
• up to 16 AF

NVIDIA introduced the first retail Shader Model 3.0 video card in the form of the 6800 Ultra in April of 2004. June of 2005 saw the refresh of that video card, the 7800GTX, which forms the basis of the 7xxx series. Key features of the 7600GS include 12 Pixel Shader Processors, 5 Vertex Shader Processors, and 8 Outputted Pixels per clock. The 7600GS is based upon TSMC's 90 nanometer low-k process, resulting in lower temperatures for the given performance metric.

The 7600GS from XFX has a clock speed of 500MHz, which is 100MHz above the reference card clock from NVIDIA and 900MHz for the memory, compared to 800MHz for the reference card. Last month NVIDIA launched the 7600GT which is priced slightly higher than the 7600GS. The reference speed for that card was 560MHz for the core and 1.4GHz for the memory. Memory bandwidth on the card is 14.4GB/second.

Key features of the card include support for Pixel Shader 3.0 and Vertex Shader 3.0. Every card sold today except for the odd S3 S27 and the XGI cards are Shader Model 3.0 compliant. PS 3.0 brings longer Shader program lengths (up to 65,536 instructions limited by the API), dynamic branching in the Pixel Shader, a back-face register for 2-sided lighting and more.

Vertex Shader 3.0 brings to the table nearly unlimited Shader length programs (65,536 instructions instead of the 256 in VS 2.0), vertex texturing (displacement mapping among other effects), geometry instancing (reuse of procedural geometry by changing the instancing streams) and more. The 7600GS has 5 Vertex Shaders, allowing the 7600GS to have a vertex throughput of 730 million vertices in a second.

Elder Scrolls: Oblivion was just released a couple of days ago. I haven't had a chance to play the game yet, but it is supposed to be a tour de force in the graphics department. Effects like realistic skin, water, armor, lighting, and parallax mapping make this game a must have for the owner of a SM3.0 video card like the 7600GS. As soon as we can get a variety of cards tested with the game in extended game play, I'll likely add a Oblivion benchmark to the barrage of tests.

F.E.A.R. was one of the scariest most graphically intense games of 2005. The first level where you basically explore and learn the controls of fighting nonetheless scared me out of my seat when the bloody face appears in the middle of the screen. F.E.A.R. uses Pixel and Vertex Shaders throughout the game. This is the type of game a card like the 7xxx and ATI x1K series was designed to play.

High Dynamic Range Lighting compensates for the fact that normal lighting has a wide range of contrasts between the brightest light and the darkest alley. The normal video card uses integer calculations to determine light intensity, with a maximum range of 255:1. HDR requires floating point calculations of 16-bit color. This allows for a range of 65,535:1, presenting more natural light. The 7xxx series is incapable of doing Anti-Aliasing+HDR at the same time unless the programmer works around the limitation as in HL2: LC with a different method. SLI brings to the table three different modes, SFR, AFR and Compatibility Mode. Single Frame Rendering has each card render a portion of the screen. Alternate Frame Rendering has each card render a single frame one after the other. AFR works best when the subsequent frame is similar to the previous frame, as each GPU is doing similar loads. SFR works best when subsequent frames are different, as each card works on part of the frame.

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