DVI and VGA cables are the two types of video cables used by the majority of the world's computers. Video cables are responsible for carrying graphical information from the computer to the monitor, and the video cable used by your computer has a great impact on the quality of the images displayed by your monitor.
Identification
Examine the connector at either end of a video cable to determine its type. A VGA cable has 15 pins, arranged in three rows of five pins each. A DVI cable will have 29 pins, with 25 of the pins arranged in three rows of eight to nine pins each, and the remaining four pins arranged in a square away from the first group. Different types of cables may be missing a small number of pins, however.
Image Quality
VGA cables are used to carry analog data, while DVI cables are digital. Very few CRT monitors support DVI connections at all, but many LCD monitors allow you to use either a VGA or DVI cable to connect the display to your computer. Connect an LCD monitor to your computer using a DVI cable if you can; VGA cables tend to produce blurry images on LCD displays.
Impact of Cable Quality
If you are using a DVI cable to connect your monitor to your computer, upgrading your cable will not improve the image quality of your monitor. However, if you are using a high quality analog CRT display, upgrading your VGA cable can make a significant difference. In digital transmissions, a signal is either received or it isn't. Analog transmissions can be degraded in quality by interference, to which inexpensive cables may be more susceptible.
Maximum Length
While DVI cables can be up to about 50 feet long before a signal amplifier is needed, VGA cables have been known to operate properly at lengths of 150 feet or more. For a very long cable run, ensure that you use a cable that is well shielded to minimize interference.
Price
BothVGA and DVI cables are inexpensive. Expect to spend approximately $10, as of 2009, for either type of cable, depending on length. A higher-quality VGA cable with extensive shielding will be more expensive, however, and may cost more.

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