There is a known bug to nvidia settings: Bug #1341140.
If you receive the following error message, you are probably affected by it:
ERROR: nvidia-settings could not find the registry key file.
This file should have been installed along with this driver at either
/usr/share/nvidia/nvidia-application-profiles-337.25-key-documentation or
/usr/share/nvidia/nvidia-application-profiles-key-documentation.
The application profiles will continue to work, but values cannot be preopulated
or validated, and will not be listed in the help text.
Please see the README for possible values and descriptions.
There is a workaround to this bug, also contained in the bug report. Execute the following from a root shell, replacing the 340.24 by the actual driver number. (I yet have to find out what they mean...)
mkdir -p /etc/nvidia
cd /etc/nvidia
ln -s /etc/alternatives/x86_64-linux-gnu_nvidia_app_profile_keys nvidia-application-profiles-340.24-key-documentation
ln -s /etc/alternatives/x86_64-linux-gnu_nvidia_app_profile nvidia-application-profiles-340.24-rc
Now the problem should be fixed, according to the bug report.
EDIT: The OP mentioned that he had to alter above commands as follows:
cd /usr/share/nvidia
mv nvidia-application-profiles-340.76-key-documentation nvidia-application-profiles-key-documentation
mv nvidia-application-profiles-340.76-rc nvidia-application-profiles-rc
Best Answer
If you have nvidia prime installed just go to nvidia x server settings and choose it in prime profile (you need to relog to apply the changes).
To install prime:
First make sure bumblebee not installed! Or just remove it:
Install:
You can also install prime-indicator for easier switching.
If you prefer to use bumblebee/have it installed you have to run the application with a command to use the video card (advantage: you don't need to relog).
To install bumblebee make sure you remove prime! More info: https://wiki.ubuntu.com/Bumblebee