'Cannot access secondary GPU' error with Bumblebee

  So to get Bumblebee to work

a) Run the following command to find out the BusID for your Nvidia graphics card:

 lspci | grep NVIDIA

The BusID is the number in the beginning of the line returned by the command above. Here's how the output for the command above looks like on my laptop:

 01:00.0 VGA compatible controller: NVIDIA Corporation GF108M [GeForce GT 525M] (rev ff)

The BusID is the number in bold, "01:00.0" in my case.

b) Now we'll have to add the BusID to /etc/bumblebee/xorg.conf.nvidia and for this, we'll open the file as root with a text editor (I'll use Gedit in the command below):

 sudo gedit /etc/bumblebee/xorg.conf.nvidia

And in this file, in the "Device" section, add the following:

    BusID "PCI:YOUR_BUS_ID"

Replacing "YOUR_BUS_ID" with the BusID returned by the command used under step a). For me (remember, for you, the BusID may be different), this line looks like this:

  BusID "PCI:01:00:0"

Then, restart your system and Bumblebee should work so when you want to run an application or game on your Nvidia card, use:

 optirun APP_OR_GAME
 optirun glxspheres

Help > W E B U P D 8 Check Bumblebee Section