The video signal - in digital form - creates a video card. A digital-to-analog converter (D / A converter) converts a digital video signal to an analog signal, which is fed to the monitor via a VGA connection. On older video cards, the DAC is a separate chip on the video card. Currently, DACs are usually embedded in a graphics processor (one for each monitor output).
With the advent of LCD monitors, the situation began to change dramatically. The new generation of displays requires digital video to work. The problem was that at the time of the appearance of LCD monitors, all existing video cards used analog VGA output. Fast - but not the best in quality! - the solution is to receive an analog signal from a video card and then convert it to digital inside the LCD monitor using an ADC (analog-to-digital converter). Of course, the quality of the video with this - double! - conversion is lost.
If the signal comes out of the video card in digital form, and the display can receive such a signal, then the transfer will occur without unnecessary conversion. It took quite a long time to adopt a single standard for digital video transmission. Finally, in 1998, Fujitsu, Compaq, HP, IBM, Intel, NEC and Silicon Image founded the Digital Display Work Group (DDWG), which in April 1999 announced the DVI Standard 1.0, the single standard for connecting digital monitors.
The DVI specification was designed with the expectation that in the future most monitors will become digital. The DVI interface is rarely used because there are still a lot of traditional CRT monitors, and because many LCD monitors are connected via an analog VGA interface.
The DVI (Digital Visual [Video] Interface) interface - a digital video interface - is gradually replacing the classic VGA connection between the video card and the monitor. Modern video cards have at least one DVI output, usually in the DVI-I variant. This connector can also be used to connect analog VGA monitors using an adapter. Most cards are equipped with a combination of one DVI-I output and one VGA. Many modern video cards are already equipped with only two digital DVI-I connectors (without analog VGA).
But since video cards without DVI output are still widespread today, many LCD monitors still have VGA input. Installing two video inputs increases the cost of the monitor. Of course, if the monitor is equipped with two inputs, DVI and VGA, then it is preferable to use digital - DVI.
DVI connector types
Currently the following DVI connectors are used:
• DVI-D - for fully digital connection in single channel (single link) and dual channel (dual link) versions;
• DVI-I - for analog and digital connections in single-channel (single link) and dual-channel (dual link) versions;
• DVI-A - for analog connection.
Most often, video card manufacturers equip their products with a dual-channel DVI-I connector, even if the card has one connector.
If your LCD monitor is equipped with only a VGA connector, then use a special adapter to connect to the video card's DVI connector (this adapter is sometimes sold in conjunction with a video card or LCD monitor).
Connect your LCD monitor via DVI and enjoy the quality of the "pictures"!