If you're using the Ubuntu operating system, then you may already know that configuring graphics cards can be challenging. However, you can still determine which graphics card you have without having to open your computer.
Open a terminal and type "lspci" (without quotes). If you can't remember this command easily, then think of the Unix command "ls" which you use to list the contents of a directory and then remember that you're listing the PCI slots on the computer. ls, together with PCI spells "lspci," which is the command you want to use.
The lspci command will return a lot of information. Look for the line that states "VGA compatible controller." Your graphics card should be listed on the same line. You may also view a line that states "Display controller," which might list a secondary controller.
If for some reason you view "unknown" devices, then type "update-pciids" (without quotes), which should update the devices. Then type "lspci" (without quotes) again.