I just installed a new video card ATI X1600 Pro 512MB PCIe (with 1 VGA input and 1 DVI input) into my DELL Dimension E510 Windows XP SP3 and download the driver for this video card and installed it sucessfully. Then I disable the integrated onboad video card and reboot the PC to use the new card. Windows boot up OK but after that the monitor display blank and even when I tried "Ctrl-Alt-Del" to access to the task bar or device manager to see what happened but nothing was displayed. I restarted the PC and press F12 to setup the system and selected the add-in video card, saved it and restarted the PC again but the monitor still displayed blank after Windows XP boot up. I tried to connect to the DVI input to a different monitor to check if the display was defaulted as the primary display or not but the situation was the same. I tried to reboot the PC and press F12 again to setup the old video card back and connected back to the old card input but the system sent a message that I should connect to the add-on video card. Please let me know what the problem is or how I can get the display with either new or old card. Thanks in advance.