If you look in the various screens, you should find something to do with on-board VGA. Failing that google for a manual for the make and model of motherboard, unless you already have one. From there you will have detailed instructions on how to disable on-board graphics. You could also just install the new graphics card without changing the BIOS, and it may work without conflicts.
-------------------- All I ever wanted was an honest weeks pay for an honest days work