Switch the graphics card used by dual system ubuntu
After selecting a proprietary driver for your Nvidia graphics card, you may need to restart your computer to enable Nvidia's prime support. If prime is not supported, you will find the following message.
Message: PRIME: is it supported? no
After restarting the computer, open the Nvidia X Server Settings window in Unity's Dash. You can also enter the following command in the terminal to open it.
nvidia-settings
Select the PRIME Profiles tab in the left column, then select the Nvidia graphics card in the right window. Open the System Settings > Details window again and you will find that Ubuntu is using the Nvidia graphics card. 
In this way, the graphics card can be set to the corresponding independent graphics card. If you want to switch back to the Intel integrated graphics card, just select Intel in PRIME Profiles.
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