Ae link muiiiiito bom sobre as diferencas do Half Life 2 em DX6, Dx7, Dx8 e Dx9.
DirectX 8 cards were the first to include programmable shaders on the GPU. These cards' shaders are rudimentary by today's standard but are very good at bump-mapping. Half-Life 2 on a DX8 board will have bump-maps on almost every surface in the game.
On a DX8 card, Half-Life 2 will use the Vertex Shader 1.1 spec and whichever version of the DX8 Pixel Shader spec that best suits your hardware—1.1, 1.2, 1.3, or 1.4. Expect to see shiny, bump-mapped water—with Fresnel reflections!—in every puddle, pond, and bay. Unlike less advanced cards, DX8 cards are also fast enough to reliably draw the output from in-game cameras. Detail props make their first appearance too, and will show up anywhere there should be rocks or grass. You'll also see the game render real dynamic shadows (albeit with straight edges). On a DX8 card, almost everything in the world can receive specular highlights; only in-game character models are the notable, non-shiny exception. Most importantly, owners of DX8 class cards will see every texture, at its full resolution, exactly as the level designer intended.
A DX8 video card won't give you all of the game's visual treats but you'll get most of the big ones. Upgrading to something newer will you at least $200, and depending on what card you have now, a video card upgrade may not be faster, just more fully featured. That said, the Radeon 9600 and 9800 cards, and the GeForce FX 5600 and 5900 are great upgrades.
DirectX 8 cards: any nVidia GeForce 3, any nVidia GeForce 4, ATi Radeon 8500 and 9x00, Matrox Parhelia, SiS Xabre
A DX9-compliant video card sports the most advanced fully programmable pixel shaders available today. Boasting support for 128-bit floating-point color, Pixel Shader 2.0, Vertex Shader 2.0, and sky-high clock speeds, the graphics chips on DX9 cards sport more transistors than even CPUs!
Running Half-Life 2 on your DX9 video card will showcase both the game and your 3D card's capabilities. You'll see detail textures to the horizon and specular highlights on everything, including other characters. All the characters will cast dynamic shadows, complete with realistic, fuzzy edges. All the water will use Fresnel reflection to determine whether it should reflect or refract light. The game will even include volumetric fog to limit your underwater vision. Bump-mapped displacement maps will add even more detail to the terrain and cavern walls. We should also note that when you run Half-Life 2 on the next generation of video cards (DirectX 10), the game may run faster than anything you'll see on a DX9 part but won't look any better.
While there are DX9-compliant cards that start at around $120, our guess is that their slow clock speeds and narrow memory pipelines won't be able to keep up with Half-Life 2's demanding requirements. We can't make any real hardware recommendations yet, because we haven't tested the game, but we'd much rather have a card that's too fast than one that's too slow. Right now, the two fastest video cards are the ATi Radeon 9800 Pro and the nVidia GeForce FX 5900 Ultra. Both are very expensive, costing between $400 and $500 depending on memory configs. That's a lot of jack, but you can rest assured that both will run Half-Life as it's meant to be seen.
DirectX 9 cards: nVidia GeForce FX 5x00, ATi Radeon 9x00
boas novas pra todos os donos de cards Dx8 de todas as marcas