First off, I have to say that for me the ditheting is also there in the BIOS screen and I am not saying this just from getting eyestrain because I now have a microscope and I have recorded the dithering.
Here's the video I recorded of my PC dithering (this exact dithering is there both in BIOS and also any OS I have installed):
https://youtube.com/shorts/5YmCl4NVrB0?si=HOucTdqZxj74wWgw
And I also want to add that its by far the most horrific degree of dithering I have personally observed with my microscope on any device :"(.
This stuff about NVRAM is really interesting. this must be the key.
I am pretty sure there is something thats getting written to the mobo that does not get effected with BIOS updates.
glvn a) the initial value of the variable from the video bios (or video chip hardware), in old cards is not set or is set as OFF
b) a variable in the uefi nvram of the motherboard, the initial value is inherited from point a) or is forcibly set to ON by “new” motherboards because it is useful for “image beauty”. This can try to explain the fact that “good” video cards perform “good” on old MBs but “bad” on new ones (including even before loading the OS).
This is exactly what I'm thinking too. And I also think the reason that we cannot set it OFF after it goes on is because no software or hardware command has ever been defined to tell the card to turn the dithering OFF. If it turns ON on a card theres no command defined ever to set it OFF again.