I forgot to check back in this thread.
I ended up using the live chat with Intel and was advised to use an older version of the driver. (An obvious solution, which worked).
This machine I have assembled will be running Linux as a small server, so getting graphics working is just a test, so not an urgent issue.
However, I then went on to Install and try Windows 8.1. Using the previous driver as suggested worked to a certain extent, but if I tried to open the Intel graphics options (from tray or desktop context menu), I would get an error message from Windows saying that it had stopped working.
A small workaround (I wouldn't recommend trying this on a production system) I found to use the latest drivers was to download the .zip drivers, open the .inf file, then make new entries for this CPU based on another server CPU already in the file. (So for each section, just copy the entries, but change the hardware id). After which, reboot, but press F8 after the BIOS to enter the Startup Settings for windows, then select Disable Driver Signature Enforcement. Then just go ahead, run the installer, then when a scary red coloured warning popup appears, just dismiss it, and the drivers will be installed.
I may end up repurposing this machine in the future as it is a nice little system, so hopefully someone at Intel will look into this and come up with a solution.