Unable to use 8bpc color depth

(I was told by customer support to post here again.)

On Linux, the nvidia driver forces 10-bit color depth on my display. I want to use 8-bit color, but the nvidia driver ignores my settings. I have selected “8bpc” in nvidia-settings, and I have set “DefaultDepth 24” and “Depth 24” in my xorg.conf settings. But the nvidia driver still forces 10bpc on the display.

The side-effect of this is that at 2560x1440 240Hz, DisplayPort DSC (Display Stream Compression) is used, which I do not want. (My display shows me the color depth the GPU is using in its OSD.)

This is not a problem on Windows, where the Windows nvidia driver uses 8bpc by default, but also has settings to choose the color depth and they actually work.

GPU: RTX 4070 Ti Super
Display: Asus XG27AQDMG (Firmware: MCM102)
Driver: 560.35.03
Kernel: 6.6.49 (LTS)
OS: Gentoo Linux AMD64
X.Org: 21.1.13
Desktop: KDE Plasma 6.1.4

The output file of nvidia-bug-report.sh is attached.

nvidia-bug-report.log.gz (823.5 KB)