[SOLVED] NVIDIA - "Can't access Secondary GPU" with Bumblebee in Ubuntu 14.04 LTS

I recently installed Ubuntu 14.04 GNOME Beta1 on my Asus K55VM laptop with NVIDIA GeForce 630M graphics. Like the previous release (Ubuntu 13.10), the LTS version beta1 release also ships with nouveau drivers for NVIDIA. Now I encountered problems of laptop overheating as the hybrid graphics are always on, which I don't require.

Hence, the best option for me was to install bumblebee. I ran the following codes in the terminal to install bumblebee:
$ lspci | egrep 'VGA|3D'
To check your drivers if you are not sure of your graphic card.

In case NVIDIA is present, proceed with the following steps.

$ sudo add-apt-repository ppa:bumblebee/stable
$ sudo apt-get install bumblebee bumblebee-nvidia primus linux-headers-generic
$ sudo apt-get install bbswitch-dkms
$ sudo apt-get install mesa-utils

Post installation of all, I added myself to the bumblebee group.
$ sudo gpasswd -a arindam bumblebee

A reboot and after that I wanted to check if bumblebee was working or not.
$ optirun glxgears

I got error something like this:

[ERROR]Cannot access secondary GPU - error: [XORG] (EE) NVIDIA(0): Failed to initialize the NVIDIA GPU at PCI:1:0:0.
Please[ERROR]Aborting because fallback start is disabled.

Now I did a fair amount of research on it, trying to find out a solution. After a lot of trial and errors, here's the solution that worked for me.

Step 1: Download the nvidia-331-updates

$ sudo apt-get install nvidia-331-updates

Step 2: Once installed open the bumblebee configuration file

$ sudo gedit /etc/bumblebee/bumblebee.conf

I had gedit as my text editor and hence, put gedit there. In case you are using leafpad, replace gedit with leafpad. In case you don't know, simply use nano - sudo nano /etc/bumblebee/bumblebee.conf

Now edit to make it look exactly the same as mine for the section on nvidia.

# Configuration file for Bumblebee. Values should **not** be put between quotes

## Server options. Any change made in this section will need a server restart

# to take effect.

[bumblebeed]

# The secondary Xorg server DISPLAY number

VirtualDisplay=:8

# Should the unused Xorg server be kept running? Set this to true if waiting

# for X to be ready is too long and don't need power management at all.

KeepUnusedXServer=false

# The name of the Bumbleblee server group name (GID name)

ServerGroup=bumblebee

# Card power state at exit. Set to false if the card shoud be ON when Bumblebee

# server exits.

TurnCardOffAtExit=false

# The default behavior of '-f' option on optirun. If set to "true", '-f' will

# be ignored.

NoEcoModeOverride=false

# The Driver used by Bumblebee server. If this value is not set (or empty),

# auto-detection is performed. The available drivers are nvidia and nouveau

# (See also the driver-specific sections below)

Driver=nvidia

# Directory with a dummy config file to pass as a -configdir to secondary X

XorgConfDir=/etc/bumblebee/xorg.conf.d

## Client options. Will take effect on the next optirun executed.

[optirun]

# Acceleration/ rendering bridge, possible values are auto, virtualgl and

# primus.

Bridge=auto

# The method used for VirtualGL to transport frames between X servers.

# Possible values are proxy, jpeg, rgb, xv and yuv.

VGLTransport=proxy

# List of paths which are searched for the primus libGL.so.1 when using

# the primus bridge

PrimusLibraryPath=/usr/lib/x86_64-linux-gnu/primus:/usr/lib/i386-linux-gnu/primus

# Should the program run under optirun even if Bumblebee server or nvidia card

# is not available?

AllowFallbackToIGC=false

# Driver-specific settings are grouped under [driver-NAME]. The sections are

# parsed if the Driver setting in [bumblebeed] is set to NAME (or if auto-

# detection resolves to NAME).

# PMMethod: method to use for saving power by disabling the nvidia card, valid

# values are: auto - automatically detect which PM method to use

#         bbswitch - new in BB 3, recommended if available

#       switcheroo - vga_switcheroo method, use at your own risk

#             none - disable PM completely

# https://github.com/Bumblebee-Project/Bumblebee/wiki/Comparison-of-PM-methods

## Section with nvidia driver specific options, only parsed if Driver=nvidia

[driver-nvidia]

# Module name to load, defaults to Driver if empty or unset

KernelDriver=nvidia-331-updates

PMMethod=auto

# colon-separated path to the nvidia libraries

LibraryPath=/usr/lib/nvidia-331-updates:/usr/lib32/nvidia-331-updates

# comma-separated path of the directory containing nvidia_drv.so and the

# default Xorg modules path

XorgModulePath=/usr/lib/nvidia-331-updates/xorg,/usr/lib/xorg/modules

XorgConfFile=/etc/bumblebee/xorg.conf.nvidia

## Section with nouveau driver specific options, only parsed if Driver=nouveau

[driver-nouveau]

KernelDriver=nouveau

PMMethod=auto

XorgConfFile=/etc/bumblebee/xorg.conf.nouveau

Once done, save it and reboot.

Now check optirun glxgears or optirun glxheads in terminal. You'll see the output shown below and withe optirun, glxgears and glxheads work 4 times faster than with Intel graphics. Also, my laptop stays ice cool even after using for 12-14 hours. I hope it helps those who are facing the same issue as I was facing.