Video is the single most important feature of a PC. Even in the two situations that don't require video, servers and blind people's computers, video is still essential. In the case of servers that aren't regularly accessed by users, you still need video on occasion for configuration, repair, and other operations. Blind people use screen readers and keyboards to use their computers, but screen readers don't work until the OS boots. Consequently, repairs and other operations often require a sighted technician to see the monitor. It is because of video's high level of importance that the BIOS allows the video adapter to provide base VGA video as soon as the computer is powered on. Base video is enough for clear text: 640 x 480 pixels (the smallest picture elements) and 16 colors. Video Graphics Adapter (VGA) is a video standard used by PCs for many years. Super VGA (SVGA) is a major improvement, but it is based on VGA and the monitor connectors are the same.

Video Adapter (Graphics Adapter, Video Card) Overview

Many computers come with video built into the motherboard. However, many motherboards don't have built-in video, and some that do also have AGP slots for additional or replacement video adapters. There are also PCI video adapters available, although PCI isn't considered the best interface for video. There are several reasons to use separate video adapters:

Users may want better video performance than their motherboard provides.

If built-in video fails or is troublesome, it can be disabled in the BIOS and an expansion card used.

Note Sometimes, inserting an expansion video card automatically disables built-in video in the BIOS.

Users might need to use two or more monitors simultaneously, and multiple adapters or a specially designed video adapter is necessary for two or more monitors. Recent Windows versions support multiple monitors for different purposes, including having all monitors show the same screen, having one screen spread across more than one monitor, or even having a different screen on each monitor. For more information on multiple monitors in Windows XP, search Windows XP's Help and Support for "multiple monitors."

Note Dualview in XP is similar to multiple monitors, but works with laptop/notetutorial computers. With Dualview, the laptop's built-in screen is the primary monitor, and a monitor that the user attaches to the external VGA port is the secondary monitor. For more information on Dualview, search for it in XP's Help and Support.

As covered in tutorial 3, there are also DVO header connectors for DVI digital video adapters in some motherboards, and built-in DVI ports in others. As of the time of this writing, most PC motherboards have either built-in VGA ports or AGP slots for VGA video cards. Digital video capability might or might not be present.

Selecting a Video Adapter

High-quality video is necessary for any graphics-intensive activities such as Web surfing, high-graphics games, video and photographic editing, and others. High-quality video has two main components: general quality of the video adapter and monitor including the chipset, and amount and type of video memory. To understand the importance of sufficient video memory, it is necessary to understand how the amount of video memory affects the screen resolution and color depth (the total number of different colors a video adapter can output to the monitor).

Video Memory

So, you can see that the capacity to display high-quality video depends on video memory. Fortunately, you can get the highest color depth and excellent resolution with amounts of memory that are modest by today's standards. People successfully use computers with 2 to 8MB of video memory, although they might see slower loading of graphics on the screen and slower Web surfing. Video adapters with enormous amounts of memory—in the 1GB range—are available. For consumer use, 256MB is the most available at this time, although this number will probably be higher by the time you read this. These high-powered adapters can provide good resolution for large-screen high definition television (HDTV). They are great for three-dimensional and other special effects, and those who are into the latest computer games will want the most video memory they can get. However, a mere 8MB allows for 1024 x 768 resolution and 32-bit color simultaneously with memory to spare, settings that are good for the vast majority of computer users with typical monitors.

Just as in main computer memory, video memory comes in different types. Single Data Rate (SDR) and Double Data Rate (DDR) are the most common types. DDR is faster, so its performance will be better. Video cards with more and faster memory have the potential to provide better performance than others, but there is a point of diminishing returns. It is probably not worthwhile to have a great video card installed in a computer with a slow processor and limited amount of main memory.

Note In some computers with video built into the motherboard, video memory is part of the main memory. There is a BIOS setting to determine how much of the main memory to dedicate to video. Unless there is a large amount of main memory, the decision becomes a trade-off between video performance and overall computer performance.

Other Elements of Quality Video Adapters

When your motherboard comes with built-in video, you basically choose graphics by the quality, features, and reputation of the manufacturer in much the same way you would choose a video adapter card to install on the motherboard. With a separate video card, however, you have more choices, and that can be confusing.

One big manufacturer of video chipsets, ATI, makes their own video cards and sells chipsets to other video card manufacturers. Even though the chipsets might be identical, video cards from different manufacturers might be different. The same is true for video chipset makers such as nVidia who do not manufacture their own video cards. Be careful to choose a company that has great support and supplies driver updates readily.