Your PC’s Video Ports
The video port has been around for many years and still rocks! Virtually all video cards still offer the same 15-pin, D-SUB video port that originally appeared with the IBM Video Graphics Array (VGA) specification.
However, another new face is on the block: the 29-pin, DVI-I port, which is used to connect digital flat-panel (also called liquid crystal diode, or LCD) monitors. This figure shows the business end of a typical video card that offers both ports onboard.
Virtually every card that has both these video ports can use two monitors at a time — either showing an expanded desktop, where your mouse moves seamlessly from one monitor to the other (like in this figure), or two separate and discrete desktops.
In a pinch, a DVI-VGA adapter allows you to use the DVI-I port to connect a standard cathode ray tube (CRT) monitor, so you can use two analog monitors instead.