second monitor by adding add-in graphic card to my dell desktop computer

[Eric Lee]

I am trying to add second monitor by adding add-in pci graphic card to my dell desktop computer. But when both monitor is connected, I got following error message, "Unsupported Video Configuration".
I am currently running Windows 7. It seems I can only use one monitor at a time. How can I use two monitor at the same time? Thank you.

 

[JKatwyopc]

Many OEM computers disable the built in graphics when a discrete video card is added. However, most current graphics cards (including low-end ones) can support two or three monitors on their own with the correct cables connected. Try hooking up both monitors to the outputs of the graphics card.