Dual output video card

Video cards with 2 outputs have become commonplace. The marketplace is transitioning to two DVI outputs on a card, but quite a few are still VGA and DVI. DVI is backwards compatible with VGA through a $5-10 adapter. When you buy a video card $50 or over, go ahead and get one with 2 outputs even if you’re not going to do multi-monitor right away. If you don’t care about 3D performance, look at Matrox as they have arguably the best multi-head software.

Dual-output video cards typically detect whether or not a monitor plugged into the second port, and if not, that second monitor option is not visible in Windows. So, you’ll need to plug in both monitors and turn them on and then boot up the computer. It will detect both monitors and allow the option of using the secondary display. Read the Enabling section below to learn how to enable the second display.

Multiple Video Cards

Windows also supports multiple monitors through installing multiple video cards. The caveat to this method is that you are limited by the number of slots on your motherboard, and many cards older than 3 years of age do not work properly in this mode. You can, however, mix and match multi-monitor cards for even more monitors with fewer motherboard slots in use.

Motherboards only have one AGP slot. Since most motherboards already have an AGP slot in use, your secondary video card will need to be PCI, which is not as fast but works fine for most uses. If you have a PCI Express motherboard, it likely has several PCIe slots, including a few x1 and sometimes even two x16 slots. PCI Express slots are faster than regular PCI slots, and x16 slots are 16x faster than x1 slots. PCI Express motherboards are thereby more advantageous for multiple monitor setups due to more available bandwidth.

Once you install each video card, you’ll need to install the appropriate video drivers for that card.