gnome - ubuntu 13.10 black screen after installing nvidia optimus drivers

I have a 3XS Graphite LG155 laptop from Scan, which has integrated intel graphics along with a 2GB NVIDIA GeForce GTX 765M graphics card.

Initially when installing 13.10 the setup was freezing but I managed to install OK by setting the nomodeset boot option at the start of the install).

My laptop is using the the integrated graphics now with the following driver: -
Gallium 0.4 on llvmpipe (LLVM 3.3, 256 bits)

I'm running Gnome 3.8.

I've attempted to install the nvidia drivers doing the following: -

sudo add-apt-repository ppa:xorg-edgers/ppa
sudo apt-get update
sudo apt-get install nvidia-331

This seemed to install fine however after a reboot all I get is black screen, and I have to use another terminal to uninstall the drivers before I get a desktop back again.

I've tried uninstalling bumblebee as suggested in another internet site, but this hasn't worked either.

Running glxgears works but very slow in fullscreen, and gnome-shell is currently maxing out the CPU when doing anything on the desktop.

I've also tried installing earlier nvidia drivers through apt-get but with the same issues.

To top it off, after connecting another monitor via the laptop's VGA port, all I can get is mirroring on it. Searching the web hints at needing the nvidia drivers installed before you can tell it to extend the desktop. Currently 'Detect Displays' doesn't see the attached monitor.

I've also gone through the suggestions here to no avail: -
After installing NVIDIA drivers, I boot into a black screen [13.10]

Any help appreciated.

Thanks

On a similar system (at least I have the same graphics) this worked for me:

First:

sudo apt-get remove nvidia*

then install bumblebee and the new drivers following this:

http://www.muktware.com/2013/12/install-nvidia-331-bumblebee-optimus-cards/18271

as far as I know only the 331 drivers support our graphics card...