Clokwork It’s weird. As you say, many people on Nvidia and creator forums claim that they have to explicitly enable dithering on Nvidia cards, even the newer ones.
Yet Seagull’s capture card experiments found temporal dithering even on older Kepler-era Nvidia cards — except when output by HDMI with Color Output set to Full. Edit: Upon reading the capture card experiments more closely, this finding was only valid for the GTX 660. Seagull found that the the GTX 550 used temporal dithering even when RBG was set to Full.
Finally, there is our subjective findings. The most sensitive on these forums, including myself, found that later 9xx cards and ALL 1xxx cards and later all cause symptoms. Some of us even found that the BIOS screen started to look “noisy” in these cards, even before OS or drivers are loaded!
I think much of this will remain an open question until we have more capture card experiments. If you search the forums you will find many who have problems with newer Nvidia cards (mega-bummer), including 2xxx and 3xxx series cards.
I will link some posts, including Seagull’s very interesting capture card experiments, when I have access to a desktop later today or tomorrow.
EDIT based on KM post: KM has a better and more succinct explanation than myself.