I have had Radeon HD7950 and i chose into the driver settings 12 bit color and all was fine with my Sony KDL-46HX720 PVA matrix Full HD TV via HDMI, even it shows 12 bit HDMI color enabled. Recently i added in addition LG PF1500 Full HD projector and i bought Radeon R9 380 card. So now i have 2 screen duplicated. I am using HDMI and Display port 1.2 to HDMI 2.0 Club 3D adapter in the same time. I tried with the latest driver, downloaded on 19 September from AMD site, later i installed latest from the Sapphire site Crimson 17.7.2 Both drivers show artifacts when i switch to 12 bit color on the currently running screen. On 10 bit no problem, also VSR is enabled on 3840x2160p. With Nvidia GTX960 no problem on 12 bit at 3840x2160p DSR enabled. The cables are ULTR HD TV HDMI 2.0b and they support 12 bit color how i know. I do not know who else to ask. I think here is the place. Please answer.
I find now that on 2560x1440p the 12 bit color run fine, i used exactly that resolution with my old HD7950 card. I do not know why with Nvidia DSR 3840x2160p is supported 12 bit color, with Radeon only up to 2560x1440p?