I am upgrading my video card and i dont understand how to disable the built in video adapter?

its a dell optiplex gx260. i bought the new video card but after the computer boots the screen goes black. any ideas?? i disabled it from device manager. and it didnt work|||You need to disable it in the BIOS. Hit Del just after the happy beep when you switch it on. Keep tapping until the BIOS screen shows up. Be careful here and only change the setting for the on-board VGA adapter. Flick through the menus until you find it.|||You have to go into the BIOS. when you 1st turn on your computer you have to hit F2 or something like that look and read screen to see which button enters setup. Then while in the bios look for on board video and disable it. Did you hook up your monitor cable to the new card or are you still on the hookup for on board. Sometimes you gotta have your monitor hooked up to your on board video till you net to disable in the BIOS then switch to the new video card.|||When the system boots and shows the Dell Screen (or is counting memory) press the Del key to have it go into bios, then go to through the options and find the Video Card options and disable it. Should be under like Integrated perephials.