jordan
And what would the bits be for non dithering ? I think you told me in the past but I totally forgot.
The register value needs to be converted to binary format. The fourth bit (counting from right to left, starting from zero) is responsible for enabling/disabling dithering on Intel iGPU/GPU. For example, in 00000000000000000000000000010000, it is equal to 1, meaning dithering is enabled. In 00000000000000000000000000000000, it is zero, meaning dithering is disabled.
Link to the Intel manual where you can find information on registers (including PIPE_MISC, which we worked with above): Intel Manual, page 688.
speaking about motherboard firmware, how would I know if a Intel arc dgpu is set to not dither?
The dGPU has its own VBIOS, and the default settings is flashed into it rather than the motherboard's firmware.
Whether there is dithering or not, in the case of a dGPU, depends on the firmware of the dGPU itself and the driver. My ASRock ARC A770 uses the same driver as yours, so we can conclude that the driver does not enable dithering, as it is absent for me by default when working in Windows 11. This means only differences in the firmware of the dGPU remain. To check this, you would need to use the method I described above, if you need to verify it specifically in Windows.
P.S. About Win10, I can't say for sure; I did all my experiments in Win11. But now I use ARC only in Linux; I hardly use Windows.