Ditherig appears to be working. It's a supported chipset, and I get no errors. PWM was not detected by camera.
The more I investigate the more I am starting to feel like our focus on the monitor is a red herring. I have 2 identical monitors, on two systems, identical OS's, identical display settings, identical monitor settings, one causes strain, one does not. The more research I do the more it points to the video card/graphics driver as the source of the issue. My one PC has a Nvidea chip in it, causes no problems, other one has Intel 5500, immediate eye strain.
We should start gathering data on the video cards in use on the computers that are causing eye strain, cause I am starting to think the monitor has very little if anything to do with it. The video card/driver seems to be causing the monitor to display an image in a way that causes the eye strain, and fiddling with the monitor likely cannot change that.