SimHQ.com - Technology Zone - Review: ATi Radeon X800 XT PCIe

As mentioned above, the Radeon X800 XT is a 16 pipeline configuration that also includes six vertex units, identical to the GeForce 6800 GT PCIe board SimHQ reviewed earlier this year. The following is a list of the features the X800 boards support:

Smartshader HD

Support for DirectX 9.0 programmable vertex and pixel shaders in hardware
DirectX 9.0 Vertex Shaders
Vertex programs up to 65,280 instructions with flow control
Single cycle trigonometric operations (SIN & COS)
DirectX 9.0 Extended Pixel Shaders
Up to 1,536 instructions and 16 textures per rendering pass
2nd generation F-buffer technology accelerates multi-pass pixel shader programs with unlimited instructions
32 temporary and constant registers
Facing register for two-sided lighting
128-bit, 64-bit & 32-bit per pixel floating point color formats
Multiple Render Target (MRT) support
Complete feature set also supported in OpenGL via extensions

Smoothvision HD

2x / 4x / 6x Anti-Aliasing modes
Sparse multi-sample algorithm with gamma correction, programmable sample patterns, and centroid sampling
Lossless Color Compression (up to 6:1) at all resolutions
Temporal Anti-Aliasing
2x/4x/8x/16x Anisotropic Filtering modes
Up to 128-tap texture filtering
Adaptive algorithm

3Dc

High quality 4:1 Normal Map Compression
Works with any two-channel data format

Hyper Z HD

3-level Hierarchical Z-Buffer with Early Z Test
Lossless Z-Buffer Compression (up to 48:1)
Fast Z-Buffer Clear
Z Cache optimized for real-time shadow rendering

Videoshader HD

FULLSTREAM technology for Real, DivX, and WMV9 formats
All-format DTV/HDTV decoding
Adaptive Per-Pixel De-Interlacing and Frame Rate Conversion (temporal filtering)

Display Features

Dual integrated 10 bit per channel 400 MHz DACs
Integrated 165 MHz TMDS transmitter (DVI 1.0 / HDMI compliant and HDCP ready)
Integrated TV Output support up to 1024x768 resolution
YPrPb component output for direct drive of HDTV displays

ATi Radeon X800 XT PCIe

While the pixel shader architecture of the R420 is nearly identical to that of the R300, the newer chip has been modified to make improvements in its rendering capabilities. The number of registers and instruction limits have both been increased, which should help performance and prevent developers from running into issues with instruction lengths while developing current and near-future engines. The X800s are, however, are still Shader Model 2.0 parts and, as such, do not support features like dynamic branching and flow control, though it’s worth noting that such features are used to aid performance and not create visual effects otherwise impossible to render without SM 3.0 support. And as with the R300 architecture, the X800s use 24-bit floating point precision throughout their rendering pipelines.

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