How do you stop your on-board video card from working?

i got an on-board video card for my PC and i have another upgraded video card installed. The old video card should not be working by this time but when I installed a certain game, the game uses the old video card and results to system crash every time I play that game. Can someone help me with this problem please?|||You need to go into the bios or config for your pc and disable the onboard video.