Ubuntu – Nvidia Graphics driver in ubuntu 14.04

1. Uninstall the NVIDIA proprietary graphics driver. Find the file you used to install the NVIDIA graphics driver from the NVIDIA website. It's in whatever folder you downloaded it to (your Downloads folder, for example). It should be named something like NVIDIA-Linux-x86_64-340.58.run. If so, the command to uninstall it is:

   sudo ~/Downloads/NVIDIA-Linux-x86_64-340.58.run --uninstall  
   sudo reboot 
   

   If the NVIDIA-Linux-x86-XXX.XX.run file has a different name or location, then change the name and/or location in the above command. The name and location of the .run file in the above command have to match exactly to the name and location of the .run file that is in your computer.

2. Run the following command to identify the recommended NVIDIA proprietary graphics driver:

   ubuntu-drivers devices  
   

3. Install the recommended NVIDIA proprietary graphics driver and reboot.

4. NVIDIA Prime is a way of adding hybrid graphics support to your laptop. NVIDIA Prime allows the user to switch between NVIDIA (Performance Mode) and Intel (Power Saving Mode) graphics from the NVIDIA Settings utility.

   If your computer has an NVIDIA 319 or more recent graphics driver installed, run the following command to install NVIDIA Prime packages:

   sudo apt-get install nvidia-settings nvidia-prime  
   

   Then NVIDIA Prime can be enabled/disabled from the NVIDIA X Server Settings application.

   

I realize this may just be linking you to another page of instructions, but this one worked perfectly for me and I keep it bookmarked as a fallback:

http://mylinuxexplore.blogspot.com/2014/03/solved-nvidia-cant-access-secondary-gpu.html?m=1

I am running on a Lenovo Y50 with an Intel i7 / Geforce GTX 860M and for whatever reason I can only get the nvidia-331-updates drivers to work as this link suggests. Literally any other nvidia driver will leave me with the same problem you are describing. It seems like its hit or miss with this Optimus technology. Hopefully we will get a good update for it in the near future.