I have hp pavilion laptop with nvidia geforce graphic card. after installing ubuntu 18.04 in dual boot with windows 8.1, which graphic card or drivers ubuntu is using on my pc?
By default, Ubuntu uses the open source nouveau driver for NVIDIA cards. I recommend you switch to the proprietary NVIDIA driver, you can do this by opening the dash and searching 'drivers', which will show an application which opens a window that then searches for drivers, from there you can select the circle next to 'nvidia-driver-390', and then click Apply in the bottom corner of the window. You'll need to restart after it has finished downloading and installing the NVIDIA graphics driver.