How to Disable an Onboard Graphics Card in BIOS
If you're looking to add video processing power to your computer, you can't go wrong installing a premium graphics card. If you've been using an on-board (or "integrated") graphics card up until this point, you'll need to disable it in order to use the new graphics card. You can accomplish this by making a change in your computer's BIOS (Basic Input/Output System). The BIOS is firmware that controls all of the hardware for your computer, including on-board devices. These steps should be done only after you have physically installed the new graphics card in the computer.
Restart your computer. While the computer is running the POST (Power-On, Self-Test) look for a message indicating a key to press to access the "Setup" or "BIOS." On most computers, the key to access the BIOS will either be "ESC," "F1," "F2," "F10" or "DEL."
Use the arrow keys on your keyboard to navigate your BIOS and use any instructions to change values. Find the menu item that closely matches "Integrated Peripherals" or "On-Board Devices." The setting to disable the on-board graphics card may also be under the "Advanced" option. Highlight the appropriate menu item and press "Enter."
Highlight the option that controls the on-board graphics card and press "Enter," then press the appropriate key to select "Disable." If your option allows you to enable an external video card, set that option to "Yes" or "Enable." If your options for the video card are "AGP," "PCI-Express" or "Integrated," choose the type of slot in which you have installed your new video card. Press "Enter."
Press "Esc" until you have backed out of all menus and are at the main BIOS screen. Select the option or press the appropriate function key to "Save and Exit." Press "Enter" to confirm. The computer will reboot and you may switch the monitor cable to the new video card output port.