So I had the nightmare scenario of my previously safe Windows 10 build starting to give me issues… restored which seemed to fix it, it started happening again and couldn't figure out why.
Anyway tried updating Nvidia drivers (GeForce 1650) and the latest app has this setting which I haven't used before..
'colour accuracy mode' originally said 'accurate', when I ticked the 'override to reference mode' box it changed to 'reference' (as per the screenshot) and BOOM.
Stress gone straight away.
Have used this morning for over two hours with no stress whatsover.