I'm using a GTX 1070, and reading what Nvidia control panel "Output colour depth" says.Chief Blur Buster wrote:Did some more research.
- I found out the NVIDIA drivers, is indeed, using 6bpc. You're right on that count.
- BUT my current NVIDIA drivers is apparently doing GPU-side temporal dithering. Neat. GPU-side FRC!
Today I learned, temporal dithering is a feature of NVIDIA graphics drivers, permanently turned on by default on Windows systems. This is a little-known feature that NVIDIA graphics drivers already is doing an FRC equivalent. There's even a little known hack to disable NVIDIA temporal dithering. Nontheless, this explains why I'm seeing 8-bit color depth with 6bpc GPU output.
Testing 165Hz (8-bit), the gradient image looks as it should.
Testing 166Hz (6-bit), the gradient looks much the same but I think I can see FRC at work. When looking closely, the grey parts appear to be slightly flickering/static, which must be the GPU-side dithering at work.
Found a post here that allows you to alter or disable dithering for the Nvidia driver.