I first installed Ubuntu 16.04 from a DVD ISO using an external DVD drive. This went ok. I firstly formatted the new data drive:

1. Install gksudo using apt-get
2. install gparted using gksudo
3. Run parted and partition and format the drive in MSDOS mode

Then I opened up the Ubuntu GUI for the installation / software update, and found that the machine was using an open source driver for the GTX 970 that was installed. It gave me the option of switching to the Nvidia proprietary driver which I did.

Then I attempted to install CUDA toolkit 7.5, and then hit my first snag, because there is no version available for Ubuntu 16.04. If you try to download the deb package anyway you will find that it will not install and complains about the signing key being too short. This is because the change to Ubuntu 16.04 has deprecated the package validation that Nvidia is using.

So therefore I started again and installed Ubuntu 14.04.4 LTS.

Then I ran into another problem which is that there was now a UI related crash on startup (unity-settings-daemon). However when I switched to the Nvidia display driver again this seemed to stop happening.