How can I make the most of my non-server hardware with server software installed?

I have a standard computer device running UBUNTU 14.04 server. I'm using it for testing but I'll need to expose my work soon enough. I have other machines laying around here - some strong, some not as much - and I was wondering how I could make the most of it.

• Is it possible to join all processing power of non-server hardware together for better performance? (like nodes?) Is there a book or tutorial on this?


• Is it possible to force all GUI processing into task performing and therefore use the visual card for extra processing power?


• How important is considering an i7 if all of the above is accomplished?


• Any extra tips on overclocking systems?

This all running linux | unix ofc.