Chapter 10: Understanding Graphics Controllers

Overview

Graphics controllers (also called video cards) are plug-in circuit boards that convert instructions from your computer's CPU into picture elements (pixels) that a video display (the monitor) uses to create images. The graphics controller is a secondary, specialized computer that has many of the same major elements as any other computer: a processor, a chipset, RAM, and an output interface. The video card usually connects to the computer's motherboard either through a dedicated AGP or PCI Express socket. In computers that use more than one monitor, additional graphics controllers can use one or more of the PCI sockets.

Some motherboards (especially the ones used in laptop computers) have an integrated graphics controller. These systems don't require a separate video card, but motherboards for desktop systems with on-board graphics controllers allow a user to disable the on-board controller and replace it with a separate card.

A graphics processor updates millions of pixels at least 60 times per second. It would be possible to perform all of this activity on the CPU and the moth-erboard, but that's less practical than using a separate processor; producing a high-resolution, full-color video image takes a lot of processing resources, so a graphics processor integrated into the computer's CPU would be a constant drain on the CPU's ability to do other work. Moving control of the video display away from the CPU allows users to choose a video card that matches their own particular requirements, without the need to pay for more performance than they need.

This chapter explains how a graphics controller converts data from the CPU to an analog or digital image, how to choose the best controller for your system, how to use Windows and other software to adjust the appearance of the image and the performance of the monitor, and how and why to use more than one monitor.

In order to understand how a graphics controller operates, it's helpful to think about the controller card and the video monitor as two parts of a single subsystem within the computer. Part of the job happens on the controller card and part within the monitor, but it's quite possible to move the controller into the monitor; that's how remote terminals work. For present purposes, this chapter treats them as two separate devices and talks about controllers in this chapter and monitors in the next.