I will create a new topic in time, I now have several identical screens and am swapping them between machines. So far this has not worked and I devloped a migraine last week and I am still suffering the after effects.
At a hardware level some screens clearly are worse than others, such as if they have PWM. But I still have screens that do not have PWM, at least not that I can measure, but cause symptoms on a machine that previosly when fitted with a good screen does not cause issues.
I had hoped it was a case of if the OS detects 'screen' it outputs to it based on what the hardware / software can handle, so getting older drivers would be OK with good hardware, then this would also be used on external screens....my thinking is that the intel graphics (what they all have) for older machines is not powerful enough to drive different monitors at different settings for colors, so they would all be GOOD. Then if you had BAD screen in laptop, external screen would be 'driven' same way and still be BAD.....if you get what I mean?
But it seems so far maybe not.
My fear is that maybe deep within hardware there are differences and even identical items are different. Perhaps other usable machines may be unusable for me if I purchase another, or an unusable machine, if I buy 20 of them for example, perhaps one of them will not affect me? I cannot afford such experiments though.