Correct way to get a GTX 980 working in Ubuntu 15.10 x64

As per nvidia's website - the matching driver is nvidia-361 for your graphics card. It's the same for my graphics card(mine is GTX 950M)

First uninstall the currently installed NVIDIA drivers. Boot the computer, when the GRUB menu appears ...

Highlight the Ubuntu menu entry and press the E key. Add nouveau.modeset=0 to the end of the linux line. Press F10 to boot the Ubuntu operating system.

When the login screen appears press Ctrl+Alt+F1. Enter your user name and the password, then execute :

sudo apt-get purge nvidia*  
sudo reboot 

Now install the latest official stable NVIDIA drivers. Boot the computer, when the GRUB menu appears ...

Highlight the Ubuntu menu entry and press the E key. Add nouveau.modeset=0 to the end of the linux line. Press F10 to boot the Ubuntu operating system.

When the login screen appears press Ctrl+Alt+F1. Enter your user name and the password, then execute :

sudo add-apt-repository ppa:graphics-drivers/ppa
sudo apt-get update
sudo apt-get install nvidia-361
sudo reboot  

Note : Maybe it is explicitly necessary to select the NVIDIA adapter in BIOS. When you want to use drivers 361, adding the PPA is not necessary. In this case the terminal commands you have to perform are these :

sudo apt-get update
sudo apt-get install nvidia-361
sudo reboot

Also if you have installed the proprietary drive from nvidia site...better to uninstall it as per the installation instructions. I have the similar kind of laptop and opensource drive is working fine for me.