Dualoutput Video Cards

In the first decade of the 21st century, most desktop computers have come with video cards preinstalled on the motherboard. But some multimedia or gaming computers use separate (or “discrete”) graphics cards, allowing for better gaming and video playback. Most of these cards feature at least two video output ports, in a design referred to as a “dual-head” card.


A dual-head or dual-output graphics card is capable of sending out two separate video signals at the same time. Most of the time, this capability is used to display a computer desktop on two monitors at once. Some graphics cards actually feature three different outputs: one or two computer outputs and a television output in the S-Video or HDMI format. Most Nvidia and AMD/ATI cards cannot use three different monitors at once, even if they have three separate outputs.

Video Ports

Depending upon which graphics card you use, your options for outputting to a monitor or monitors will vary. At the very least, modern graphics cards feature one dual-link DVI port. Mid-range and high-end cards feature two DVI ports. Low-end cards may only feature one, or may use a combination of one DVI port and one VGA port. If your monitor only uses one of these standards, you can use a converter couple to change the output of the card from DVI to VGA or vice versa. Some cards also feature an S-Video port, and most modern high-end cards will feature an HDMI or Mini-HDMI port.

Dual Monitors

To use two monitors at a time with your desktop computer and discrete graphics card, plug the computer and the monitors into an AC wall outlet. Turn on your computer and log in. Right-click the empty area of the desktop, then click “Screen Resolution.” (On Windows Vista, click “Personalize,” then “Display Settings.” On Windows XP, click “Properties,” then “Settings.”) Click on the disabled monitor, then in the “Multiple Displays” menu, select “Extend desktop to this display.” You can click and drag the displays to move their virtual location to correspond with their physical placement. Adjust the resolution to its highest setting, then click “OK.”

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Multi-Card and Multi-Monitor Setups

If your desktop computer’s motherboard supports multiple graphics cards, you can use two or more to create arrays of monitors. More than three monitors on one computer is not really practical (and very expensive) but some enthusiasts enjoy maximizing their desktop area. If your motherboard supports SLI or Crossfire technology, you can combine two or more cards to increase graphical performance. Some AMD/ATI cards and specialty manufacturer cards like Matrox offer support for up to six monitors running off of a single graphics card. You can also use an inexpensive USB-DVI or USB-VGA converter for easy monitor expansion.