A Basic Guide to Video Cards

A Basic Guide to Video Cards
Posted :: May 11, 2004 by Haggs

We’ve had a few requests for articles that will bring readers up to speed on the various terms and jargon associated with the many aspects of a computer article. We hope that this will bring readers up to speed so they will get more out of our ‘advanced’ type articles. As the first in a series of many beginners guides we hope you find this informative and simple to follow.

Let’s start by defining some of the terms that are commonly used when talking about video cards. Note that video cards are often called graphics cards, AGP cards, graphics processing units (GPU’s), or graphics accelerators.

AGP – This stands for Accelerated Graphics Port. It is the slot on the motherboard that the physical video card connects to. They come in many different speeds 1x, 2x, 4x, and 8x. Most of the motherboards on the market today have an 8x AGP slot. Each faster slot is backwards compatible with all slower speeds. This means if you have a video card that only runs at AGP 4x, it will be perfectly ok to connect it to your AGP 8x slot.

PCI Express – This literally stands for Peripheral Component Interconnect Express, but it acts much like AGP. It can transfer data twice as fast as AGP 8x. PCI Express is a relatively new technology and is slowly phasing in to use. Currently it is unnecessary for most people to have PCI Express capable motherboards because even the latest lines of video cards (nVidia GeForce 6800 and ATI X800 Pro and XT) do not even completely utilize AGP 8x. Motherboard manufacturers hope that this new technology will eventually become a universal motherboard slot that is used by all PCI and AGP cards.

Core – The core of the video card acts much like the processor of your computer. It works as the brain to control the rest of the video card’s activities.

Memory – Think of the memory as extremely fast RAM (random access memory). It is specially designed for very fast speeds.

Driver – A driver is a small program that you install (or in some cases is installed automatically by newer versions of windows, namely XP) which tells your operating system (Windows, Linux, Mac OS, etc.) how to use the video card inside your computer. Without this driver program your operating system cannot effectively make use of the video card.

Resolution – The resolution refers to the level of detail that can be distinguishably displayed on your computer’s monitor. Common resolution settings are 640 x 480, 800 x 600, 1024 x 768, 1024 x 1280, and 1600 x 1200, where higher numbers represent a higher resolution. The first number before the x represents the number of pixels that are displayed horizontally while the second is the number displayed vertically. The greater the number of total pixels, the more accurate an image can be displayed.

Color Depth – There are two common choices for color depth (or color quality), 16-bit and 32-bit. Using a 16-bit color depth requires less work to process than does a 32-bit depth because it displays fewer colors. For most practical purposes 16-bit depth (millions of colors) is more than plenty, while 32-bit depth (billions of colors) is good for those picky about their graphics. If you are looking to increase your frame rate and willing to sacrifice an almost unnoticeable amount of color difference, choose 16-bit depth in your application or game’s video settings.

Frame Rate – This is typically measured in frames per second (FPS). Video cards render (or generate) frames based on what the program tells them to show on your monitor. It works much like a giant, digital filmstrip. The frames are shown by your monitor in rapid succession to make images appear to move on your screen. The typical human eye cannot tell the difference between anything over about 40 frames per second. Research tests vary slightly in the exact frame rate, but 40 frames per second is a good approximate number. (Movies in theaters are run at approximately 30 frames per second.)

FSAA or AA – Full Scene Anti-Aliasing or Anti-Aliasing refers to the smoothness of graphic edges. In many game applications the edge of a shape looks jagged or stair-stepped. This is known as aliasing. Anti-Aliasing requires more video card processing power to perform, because it has to do extra work to smooth out these distorted edges. Most of the time it takes more video card processing power to get rid of the jagged edges than it’s really worth. If it’s available in your favorite game or 3D application, give it a try for yourself and see how your own card performs.

Polygon – A polygon is simply an enclosed shape. It can be a triangle, square, or even an irregular shape. Many games and 3D applications make use of polygon’s to form the general shapes that make up their 3D models. 3D models are created initially with a polygon frame and then shaded to give them their full 3D appeal. The greater the number of polygons used on a model, the greater the detail of that model.

Anisotropic Filtering – It is a relatively new technology that allows video cards to actively display optic distortion. For example, when a human looks into the distance eventually things fade away into the horizon. Without anisotropic filtering things in the distance would go from completely there in full detail to completely gone. Another example is the optic distortion that occurs when a human looks into a pool of water. Have you ever seen some fish swimming that appeared to be right beneath the dock, though they were actually a little distance away? With anisotropic filtering in today’s games and 3D applications it allows programmers to create more optically realistic environments.

Pipeline – Pipelines are paths for data to be transferred and processed. They act much like real pipes would in a plumbing system. say for example a single pipe can move 1 gallon of water per minute, then 8 pipelines can move 8 gallons per minute. Similarly, one pipeline on a video card can process x bytes of data per second, while 8 pipelines can process 8x bytes of data per second. Most video cards have 4 or 8 pipelines, but new ones have 12 or even 16. The efficiency of the pipelines on video cards varies by manufacturer. This means that while more pipelines is generally better, comparing an nVidia card with 8 pipelines to an ATI card with 8 pipelines will not always equate to equivalent performance.

DVI Output – This literally stands for Digital Video Input Output, which may seem contradictory at first, but really works out just fine. It is an output on the back of a video card that connects to a cable that then connects to the digital video input of a monitor. Typically LCD (liquid crystal display) monitors support digital video input, however conversion devices are created to convert DVI to VGA.

VGA Output – The video graphics array is the most basic video card to monitor connection type. It literally stands for Video Graphics Array (or Adapter). Nearly all CRT monitors connect to a video card using VGA. As with DVI, converters are made that will convert VGA to DVI (though a slight clarity loss will occur).

CRT Monitor – The Cathode Ray Tube monitor creates images on the screen by firing electrons at high speeds toward the front screen to create the different colors and images. CRTs tend to have higher refresh rates than LCD’s, but have poorer color quality. Simply, by the technique used for CRT monitors, they flicker and can cause headaches after long use. If you want to see the flicker, look at a CRT monitor out of the corner of your eye and you should see what we mean.

LCD Monitor – The Liquid Crystal Display monitor creates images on the screen by exciting a crystal structure that’s partially in both a solid and liquid state. Light is then shined through the structure and refracted into the different colors. Since the crystal structure only changes where it is needed instead of the whole screen constantly being refreshed by electrons, there is no flicker. Many businesses are switching over to LCD monitors in the workplace to reduce headaches. Another property of LCD monitors is a high sensitivity to extreme temperatures. If they are too cold the crystals will completely harden and may crack the screen, and if they are too warm the crystal structure may melt completely and turn into a pure liquid.

So let’s check your progress. You plug the video card into the AGP or PCI Express slot on your motherboard and you don’t have to worry about backwards compatibility between AGP 8x and AGP 4x, 2x, or 1x. The two basic parts of a video card are the core and the memory and they are responsible for the overall ability of the card to create graphics on an LCD or CRT monitor. LCD monitors are usually plugged into your video card by DVI while CRT monitors are normally connected with VGA. After connecting the video card to the motherboard and the monitor you can install the driver so you you’ll be able to change the resolution and color depth to something that looks nice. If you want some exceptionally pretty graphics you can try pumping FSAA or anisotropic filtering through the pipelines. If all goes well you’ll have a high frame rate and watch those polygons fly by!

How’d you do?