Matrox G400

Lore & Background

The G400's graphics processor uses a 256-bit DualBus architecture, an evolution of the G200's 128-bit DualBus, consisting of twin unidirectional buses for increased internal data flow efficiency. Its 3D engine has two parallel pixel pipelines with one texture unit each, enabling single-pass dual-texturing. The chip supports Environment Mapped Bump Mapping (EMBM), a texture-based surface detailing method created by BitBoys Oy and licensed to Matrox, which saw limited use due to lack of industry-wide support. The G400's rendering pipeline uses 'Vibrant Color Quality 2' (VCQ2), performing all internal 3D calculations with 32-bit precision to prevent dithering and artifacts. The G400's most notable feature is DualHead, which allows driving two separate monitors to display a single desktop, with modes for desktop widening, cloning, and DVDMAX (outputting video overlays to the second monitor). The card does not support full DVD decoding hardware acceleration, lacking IDCT and motion compensation in hardware. The G400 was known for its high-quality analog display output, setting a benchmark for signal quality for several years. It was the first Matrox board compatible with AGP 4X, though most REV. A boards only support 2X mode, with later REV. B boards being fully 4X compliant. Performance-wise, the G400 was heavily dependent on the host CPU for high 3D performance, attributed to its architecture and initially poor drivers. Its triangle setup engine, the 'Warp Engine', was slower than competitors' counterparts but was programmable. The card launched with an OpenGL-to-Direct3D wrapper driver, later replaced by the 'TurboGL' mini-ICD supporting SSE1 and 3DNow!, and finally a fully compliant OpenGL ICD in mid-2000. The G400 received official driver updates into 2006.

Reader's Guide

The Matrox G400 was a competitive graphics card in its era, particularly in 2D and Direct3D performance, going head-to-head with the NVIDIA RIVA TNT2, 3dfx Voodoo3, and ATI Rage 128 Pro. Prior to the release of the NVIDIA GeForce 256, the Millennium G400 MAX was a respectable Direct3D card, competitive with the Voodoo3 3500 and TNT2 Ultra. Its DualHead feature gave it a decisive edge over competitors, and its high-quality analog output made it a benchmark for signal clarity for several years. However, the G400's reliance on the host CPU and its initial driver problems, especially for OpenGL, hampered its performance. The card's EMBM feature saw limited game support, with only titles like Dungeon Keeper 2 and Millennium Soldier: Expendable using it. The G400's legacy includes its role as a precursor to the G450, which was primarily a die shrink of the G400 core. The Marvel G400-TV variant, using a Zoran chip for hardware MJPEG compression, had driver support discontinued early due to incompatibility with Windows 2000, though hacked drivers later enabled limited functionality.

Did You Know?

• The G400's DualHead feature supports desktop widening, cloning, and a DVDMAX mode that outputs video overlays to a second monitor.
• The G400 does not perform inverse discrete cosine transform (IDCT) or motion compensation in hardware for DVD decoding.
• The G400's EMBM feature was created by BitBoys Oy and licensed to Matrox, but was not supported by NVIDIA's GeForce 256 through GeForce 2.
• The Millennium G400 MAX had the highest memory bandwidth of any card before the release of the DDR-equipped version of NVIDIA GeForce 256.