Share 'Render farm OS'

We've just added a couple of powerful servers onto our render farm, but they are only running steadily at 40% capacity. Both machines are running on Windows 2012 Server. Would this make any difference? They both have quad 10 core processors and all seem to be running. In comparison, the dedicated render farm bounces up and down between 50% and 80% as it runs through a render (running on Windows 7…