macOS 10.13 (MacBook Pro Retina 13" Mid-2014) - 4K@60Hz not supported over HDMI - GTX 1060
I recently purchased two Samsung U28E590D 4K monitors. I am using DP for the first display and HDMI for the second. After setting everything up and trying 3 different HDMI 2.0 supported cables, I realized that Mac doesn't support 4K@60Hz over HDMI. Even though the HDMI port in my GPU is HDMI 2.0b and should support 4K@60.
I tried using the same setup in windows and both displays work perfectly at 4K@60. So this is not a hardware issue, rather it's some weird software issue where MacOS is just not allowing the GPU to run a display at 4K@60Hz over HDMI. I have tried disconnecting the DP display and just connecting one display over HDMI, in which case I see the option to run the monitor in 1080p HiDPI mode at 60Hz but selecting that option results in a black blinking screen on the monitor and my internal display flickering as if I am continuously connecting and disconnecting the display.
Mid-2014 MacBook Pro Retina 13"
GTX 1060 6GB
This is a known issue with macOS - and I have experienced it firsthand. My setup is also 2 4k60 monitors. Only DP outputs at 60hz on macOS. Windows is gold.
Give the following a try, no Idea if it will work.
@mac_editor Thank you for clarifying that. I was breaking my head over wires and HDMI protocols. Do you know if there is thread for tracking that issue so that I can stay updated on the topic.
@izak_filmalter I tried the coreDisplay patch based on the author's last commit. The patch just added the option to switch to 4k@60 in the SwitchResX menu. Although, selection that options causes the display to start blinking as if I were continuously connecting and disconnecting the source cable.
@akash4393 I have asked dev relations about this and apparently they have simply not incorporated HDMI 2.0 as of macOS 10.13.4. However, in my testing with the 1070 eGPU, I was able to output 4k60 (Web drivers probably support this) on the eGPU monitors via HDMI. By default, it was at 30Hz, but I noticed in Display settings that it was set to "scaled". Setting it to "default - best for display" worked. Maybe check that.