From what I can guess, it's some sort of conflict with G-Sync (the other person with a similar issue also had a G-Sync monitor). You can try disabling G-Sync, but I'm not sure that will actually solve anything.
Do you happen to have a normal monitor you can switch in to test? I'd like to see if this is G-Sync related.
Update: I did manage to get the rig with the Gsync monitor going, kind of! Extended mode doesn't have the misaligned screen that Direct mode does... But when in Direct mode, whilst the Demo Scene doesn't align (as in the photo above) when in iRacing it works absolutely fine! Tested TimeRifters via Steam but that had the misalignment problem... Strange!?
Anyway, did manage to demo ED and iRacing properly so that's the main thing, they guys loved it! Just hope there's a simple fix for my problem 🙂