Well I started again, and upgraded my box to Ubuntu 16.04 LTS. I wanted to be more up to date, and also since starting this project I have learned a heck of a lot about Linux and so I am not struggling quite so much understanding installation, and I wanted to get everything consistent.
I still actually don't have 4 GPU cards in there. The reason being that they have skyrocketed in cost because everyone is mining bitcoins. I mostly have been ensuring the software is consistent and things work ok on the setup I have. I do hope to expand it soon.
I also upgraded the board firmware which is a case of downloading from manufacturer's site and putting it on a blank USB stick and then getting into the settings on startup (which is a challenge because it boots so fast) and finding the BIOS upgrade options.
I'll write more about other installation stuff later.