An overview of Graphics cards
Graphics cards are the second most common upgrade for a computer (additional memory being the most common). Even the most undemanding user may have a need for more graphical power, especially as newer operating systems introduce more graphical tricks on the desktop. While gamers get all the attention for needing extremely powerful cards that can keep up with the ever more demanding games being released, they are not the only ones who can use a graphics card upgrade.
Generally speaking, there are two types of graphics: 2D and 3D. Two-dimensional graphics are familiar to everyone. Windows, word processing, and this Web page are all rendered in 2D. Everything has its place on the screen. The list of objects and their places are fed to the graphics card, which is then turned into a video signal that gets passed to the monitor. Three-dimensional graphics are a bit more complicated, as everything has a place in a three-dimensional space, and the graphics card is given the task of figuring out just what is seen at all. It also has to figure out which side of an object you see, whether part or all of it is hidden behind another object, or how big it should appear given its size and distance.
Three-dimensional graphics are more complicated, especially as current games utilize complex texture systems and lighting effects, which add to the load. Current cards are pretty well geared toward increasing their ability in this field, and reviews follow suit.
However, that isn't to say that 2D graphics can't stress your system. The applications are just more specialized. Any artist or graphic designer who has worked extensively on a computer knows how large images can bring a system to its knees. While part of the load devolves onto the main system, video memory is a key factor in minimizing the problems.
Also, not all 3D graphics are done on the video card. Computer animation typically involves many times the amount of detail used in computer games, and most of the work of final renders ends up being handled by the main CPU.
The memory on graphics cards is generally a step or two ahead of main system memory in terms of speed. The intense parallel-processing environment of 3D rendering requires a lot of memory usage and memory that can respond quickly to requests.
This need for speed also extends to the bus, or main connection to the rest of the system (which means the type of slot it uses). The Peripheral Component Interconnect (PCI), the standard computer interface, was sufficient for most add-on cards for about a decade, but was not nearly fast enough to get data from the hard drive and RAM to the video card. The Accelerated Graphics Port (AGP) was a specialty type of PCI bus just for graphics cards that got speed upgrades over time. Now, both PCI and AGP are going by the wayside (something to keep in mind if you have an older system) in favor of PCI Express. Video cards have naturally led the way to this new, faster (and more flexible) interface. Normal cards need but a single channel (PCI Express x1) to handle their bandwidth needs, but video cards typically use 16 (PCI Express x16) to carry their data.