graphics adapter : Computer Hardware Buyers’ Glossary

by Roedy Green ©1997-2009 Canadian Mind Products
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graphics adapter

The graphics adapter is card that fits in the AGP slot (or one of the PCI slots in older computers) that generates the image that appears on the screen. The image is made of dots called pixels. For example, on a 17" monitor the image might be 1024 dots wide by 768 deep. There are thus 786,432 pixels. People with 21 inch monitors may have an image 1280 × 1024 pixels. The smallest monitors might support only 640 × 480 pixels. About 70 times a second, the graphics adapter sends the entire picture, dot by dot, to the screen. For high resolution colour, inside the video graphics adapter, there are three numbers for each dot. One tells how red the dot is, a number from 0 for no red, to 255 for very red, one tells how green it is, and one how blue. 0,0,0 is black. 255,255,255 is white. 255,0,0 is bright red. 0,255,0 is bright green. 0,128,0 is dark green. 0,255,255 is bright yellow. The computer changes the picture by manipulating the numbers associated with each pixel. This scheme gives over 16 million colours. Low res colour might have only one number 0 to 15 associated with each pixel. This works much faster and requires less hidden RAM on the video card, but allows only 16 different colours on the screen at once. A compromise might be 256 or 65,536 different colours.

Most graphics cards today go into a special PCI-Express-16 aka PCI-E slot. Older motherboards use an AGP slot. Modern graphics cards use a digital DVI-D external connector or an integrated analog-digital DVI-I external connector. High end ones use HDMI connectors.

Sometimes the video adapter in integrated into the motherdoard. Add on cards cost from $60.00 CAD to $600.00 CAD . Gamers can spend even more on the video card than they do on the computer. Features to look for:

Video processor speed in MHz or GHz. Bigger is better, possibly dual processors for the high end.
Video RAM size. in Mb or Gb. Bigger is better.
DVI or HDMI connector (modern monitors are digital).
Fits in a spare slot of the right type on your motherboard.
Maximum resolution. It should be at least the max resolution of your monitor.

analog VGA

digital DVI-D

integrated DVI-I

AGP
GPU
graphics accelerator
List of Video cards that support multiple monitors
NVIDIA
resolution
Video card benchmark comparisons
video-drivers.com

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