Dell Optiplex GX620, Windows XP, I wanted to install a better video card than the one onboard. The manual said first disable the onboard video before installing the new card. I went into control panel, Display, Settings, Advanced, Properties, Device usage, selected Do not use this device (disabled). On reboot, I thought I would get a crude 16 colors display but instead the screen is completely blank. The computer works but I cannot see the anything. How can I change the Device usage to Use this device (enabled)? Any help would be much appreciated.