This worked perfectly on a Asus Zenbook Pro Ux501Jw running GTX 960M in secondary GPU mode (Optimus).

Steps:-

1. First step after installing Ubuntu is to install all updates. You may use the software updater or simply run:

sudo apt-get update && sudo apt-get upgrade

2. Add the Xorg-edgers ppa using

sudo apt-add-repository ppa:xorg-edgers/ppa

sudo apt-get update

Important Step =>

sudo apt-get upgrade && sudo apt-get dist-upgrade

3. Now Install bumblebee and Nvidia drivers using

sudo apt-get install bumblebee bumblebee-nvidia primus nvidia-352

4. Add the current user to the bumblebee security group.

sudo useradd -G bumblebee yourusername

For Ubuntu 15.04 only: you need to manually enable to bumblebee daemon using

sudo systemctl enable bumblebeed`

5. This will take care of the Installing the required software on your system. We need to configure it.We start by enabling bbswitch and intel i915 Driver.

sudo -H gedit /etc/modules

Ubuntu 15.04: the file is /etc/modules-load.d/modules.conf

Add these two lines to it

i915

bbswitch

6. Edit the bumblebee configuration file.

sudo -H gedit /etc/bumblebee/bumblebee.conf

1. line 22:

Driver=nvidia

2. line 55:

KernelDriver=nvidia-352

3. line 58:

LibraryPath=/usr/lib/nvidia-352:/usr/lib32/nvidia-352

4. line 61:

XorgModulePath=/usr/lib/nvidia-352/xorg,/usr/lib/xorg/modules

7. In addition to this there is another file that needs to edited.

sudo -H gedit /etc/modprobe.d/bumblebee.conf

Add this line at the end.

blacklist nvidia-352

Now you may reboot. After reboot, check using sudo apt-get install mesa-utils if mesa-utils is not already installed.

$> optirun glxinfo | grep OpenGL

OpenGL vendor string: NVIDIA Corporation
OpenGL renderer string: GeForce GTX 960M/PCIe/SSE2
OpenGL core profile version string: 4.3.0 NVIDIA 352
OpenGL core profile shading language version string: 4.30 NVIDIA via Cg compiler
OpenGL core profile context flags: (none)
OpenGL core profile profile mask: core profile
OpenGL core profile extensions:
OpenGL version string: 4.5.0 NVIDIA 352
OpenGL shading language version string: 4.50 NVIDIA
OpenGL context flags: (none)
OpenGL profile mask: (none)
OpenGL extensions:

This should tell you that nvidia-352 driver in use.

Please note that nvidia-352 is the latest driver at the time of writing this.

Abdridged from

http://askubuntu.com/questions/452556/how-to-set-up-nvidia-optimus-bumblebee-in-14-04