How do I Enable My Integrated Video Card Again?

I bought a video card 2 days ago and it was the nvidia geforce 8600 gts. Everything went great until it needed power. I still need to buy a power supply but i tried it without power and it still worked. I saw forums saying not to do that because it will cause damage. When i inserted the card into my motherboard and powered up the computer i had to install the drivers. Once i did that i disabled my old video card (It is integrated into the motherboard) and it automatically used the new one. I need someone to help me enable my old integrated video card because i really don't want to damage my new one.|||go back into bios and re-enable it