How It Works: Graphics Boards

Graphics Board: A system component, usually an expansion card, that produces 2D or 3D images on a CRT monitor.

As one of the most important parts of your PC (other than the CPU itself), the graphics board translates the binary ones and zeros of computing into the images that we can interact with on our monitors. Simply put, we couldn't use computers in many of the ways we now do without advanced graphics technology.

Here are the vital stats:

• Graphics boards handle all 2D and 3D calculations and rendering, offloading these intensive tasks from the CPU.
  
  
• State-of-the-art graphics boards cost around $300, though you can find reasonably speedy 3D performers for about half that price.
  
  
• New graphics chip sets increase graphics board performance, and vendors release new chip sets about every 6 to 12 months.
  
  
• Nearly all modern graphics boards connect to the Accelerated Graphics Port slot in a PC and sport at least 16MB of onboard memory.
  
  
• Only the most advanced 3D games and high-end computer-aided design come close to taxing modern graphics boards' abilities.
  
  

Images you see on your monitor take a complex route from inside the PC. When the application you're running wants to create an image, it sends a request for help to the part of the operating system that connects to the graphics board (called the graphics driver interface). In response, the graphics driver--software that acts as a go-between for the OS and the graphics board--listens to the instructions from either the OS or the application, then takes the digital data and converts it into a format that the graphics board can understand.

Next, the driver pipes the newly formatted digital data to the graphics board for rendering. If you have a PC made after 1998, the data travels to the board via a slot on the motherboard called the Accelerated Graphics Port. (Older PCs don't have this AGP slot, so their graphics boards plug into a standard PCI slot.)

The data's first stop, once pumped into the board, is the temporary storage space of memory, either on the board itself or inside system memory. Then the board's processor, called the graphics processing unit (or GPU), turns the digital data into pixels, the sets of colored dots that make up any image you see on the monitor. The volume of pixels produced by the board is enormous: When your screen resolution is set to 1024 by 768, the graphics board calculates the precise color for, and produces, data for 786,432 pixels to draw the screen---and it repeats this process 30 to 90 times each second.