Thanks for the comments guys. To answer them in brief:
You can not disable the on board graphics as the optimus tech is built in and not a bolt on.
Halogen seems to be having the same issues as myself in that you just CAN NOT disable the tech.
Franzuu - unfortunately putting what you have written into launch options prevents DayZ from running at all. I have tried it with more / less / different spacing but to no avail. Is there a way to force DayZ's resolution?
The problem is still there:(