- 2D or 3D: that is the question
- PCIe or AGP
- Graphics card models
- ATI cards
- ATI variations
- Nvidia cards
- Nvidia variations
- What the specs mean
- Other features
- Other components
- Power usage
- Integrated graphics
Detailing how 3D graphics works is an entire guide in itself, but the digest version is that there are two main tasks to be completed. The first is lighting and geometry, the second is rendering.
For the first, think of the 'wireframe' 3D images you've seen in documentaries and the like. These wireframes define the shape of the objects in the scene. This is the geometry of an image, and has to be calculated based on what the viewer can and can't see of the objects, the positioning, camera angles and the like. Lighting - figuring out where the light sources are and what effect they have on the objects also happens in this phase.
The second phase of drawing a 3D scene is the rendering -- that is, the painting of the wireframe. Textures are applied to surfaces, and modified according to light and other factors.
At one time, 3D graphics cards did not do any geometry processing, leaving that entirely to the computer's main CPU. Since the introduction of the Nvidia GeForce however, consumer graphics cards have possessed considerable geometry processing power - it was with the introduction of this chip that we first saw the term "graphics processing unit" (GPU) appear.
The GPU is a small microchip present on most modern graphics cards. They are specially geared towards processing complex, graphical algorithms that previously fell to the CPU. Thus, they both take the strain off the main CPU, and process information faster thanks to specialised design.
In addition to the raw ability to draw the wireframes, animate and paint them 60 or more times per second, graphics cards also have a large set of other 3D features designed to make scenes look good. Graphics cards can be differentiated by their ability to calculate shadows quickly, eliminate pixilation, render distant objects at low resolution, modify surface textures on the fly and a host of other capabilities.