Finally figured out how to run the old 1060 card downstairs for 8bit 444 4K120hz.
Gotta delete all the 4096 × 2160 resolutions and 3840 x 2160 resolutions from the EDID.
Then make sure the inserted timing is < 25.92Gbit. DP spec is 32Gbit, but actual payload spec is 25.92Gbit. Basically 3840x2160x120hz@8bit_444 is 25.82Gbit, that's pretty much the max.
On the old 10 series cards, they did not properly support DSC, Higher refresh than 120 @ even 8 bit won't work with 444 chroma.
This is a blessing and a curse.
Blessing because DSC is a compression algo, NOT lossless, it's between 2 to 3.75 : 1 compression depending on implementation. Not using it is a GOOD THING visually.
Curse, because well, you can't output 4K144hz or 4K240hz 4:4:4 under any circumstances from the 10-Series gpu, because it will exceed 25.92Gbit DP connection. Whereas, if 10-Series did support DSC properly, then you could theoretically output 4K 240hz 10bit w/ DSC 3:1 compression, which only comes out to 22Gbit.
AGAIN, DSC is NOT lossless, it damages the image quality.
