What is DirectX 11?
DirectX is a system designed by Microsoft for programming multimedia software, such as PC games or DVD or video players. Prior to DirectX, games were written largely for MS-DOS in the mid-1990's, and some Windows games were starting to be made due to the growing popularity brought by Windows 95. The Direct aspect comes from a need to standardize the way things are programmed, in order to make great, high-speed, fast action games available to a broad array of different computers. Before, programmers would write their games either based on development instructions from a component manufacturer, like for Creative Labs' Sound Blaster sound card, or a 3D add-in card. Or, they might use software called middleware to write, to use more generic programming that the middleware then handled, allowing different brands of sound cards and graphics cards to be used in different computers. So DirectX was conceived to be a standard especially for Windows games that allowed a game developer to program a game for Windows that would hopefully allow a variety of computer hardware components (add-in cards) to be used with a minimal difference in performance compared to writing software directly (strictly) for one brand or component. In a way this leveled the playing field with a standard that all hardware companies would be expected to follow.
DirectX was originally a collection of different interface specifications for handling different computer parts. It included DirectDraw for 2D graphics, DirectSound for controlling audio chips, DirectInput for handling mice and joysticks, and some others. Eventually the now defunct DirectSound 3D came out to try to unify different 3D surround audio standards into one collection of programming techniques and methods. When DirectX 3.0 came out, Direct3D was introduced to replace various proprietary 3D graphics interfaces.
PC games are designed around what is called an engine. This is chiefly thought of as a graphics framework that will typically provide three dimensional effects, taking walls, surfaces, and objects made of polygons and triangles and scaling them in size as the player moves around. Some games are designed for one version of DirectX, and sometimes subsequent games have different enhancements made available from a new DirectX version, added in. Game engines are largely modular, such that the game developer could change the graphics and some of the rules and make a new game. When an amateur does this it is called a mod. Among the biggest online games are or were, Counter-Strike and Team Fortress, which started out as mods.
So DirectX 11 is the latest standard in primarily, 3D graphics effects and technology, for PCs. While it's a programming system, and in that respect the technical details could be very mundane and boring, it's exciting for the gamer because it allows for more detailed and more realistic videogames than ever.
Some games require a certain minimum level of GPU (graphics card or graphics chip). This would be indicated on the game packaging, or in the System Requirements for a downloadable game before you buy it. A game might be made with DirectX 11, yet require a DirectX 9 GPU as a minimum. This means that with a DirectX 8 GPU the game would refuse to run. With a DirectX 9 GPU it would likely not look as good as if you had a DirectX 10 or 11 GPU. Other games like Valve's Half-Life series using the Source engine actually have distinct engines compatible with DirectX 7, 8, 9, and 10. Half-Life and its spinoffs like Counter-Strike and Team Fortress are playable on a variety of different levels of PCs. Today's game consoles top out at around a DirectX 9 capable graphics level. Therefore PCs have exceeded the technical graphics capabilities of game consoles since around mid 2007 when DirectX 10 games like Crytek's Crysis began to appear. Even prior to this it was possible to combine two GPU's in one gaming computer for over twice the graphics power of a current generation console.
Note that cheaper, weaker graphics may be genuinely DirectX 11, but it may only be playable at DVD resolution, or perhaps around 1024x768, which was a popular PC screen resolution prior to widescreen LCD monitors becoming popular. Since the mid-2000's those resolutions have fallen far out of favor. So if your graphics are underpowered you're not going to really be able to enjoy all that DirectX 11 games potentially have to offer with regards to what today's top PC games can really do with a fast computer. Indeed in a head to head comparison, the fastest available CPU with a low-end GPU could be easily embarrassed by a more mid-range CPU with a more powerful GPU, when it comes to gaming. In fact the cheaper DirectX 11 GPU's available with other computer companies may run a game faster in DirectX 9 or 10 mode, being largely unplayable in the native DirectX 11 mode, depending on your desired resolution. Aside of screen resolution, the power available with a GPU affects how much detail can be applied in a game scene. There can be a big difference between a lower end GPU (especially integrated graphics) powering a resolution of 720p, and an enthusiast-class GPU.
Since DirectX 10 was released exclusive to Windows Vista in 2007, some DirectX 10 games will only run on a newer PC with Windows Vista or Windows 7. DirectX 11 games will also only run at this time, on Windows Vista or Windows 7. The bottom line is that great new videogames are going to look and play best on a powerful new PC with Windows 7, and KillaRad is aiming steadily to be the best value in gaming PCs at all times.
Updated July 5, 2011