Sorry for my English.
I have a 4K monitor with HDMI2.0.
After I set UEFI boot, I found that the display can only display the UEFI boot screen at 2560x1440 (60Hz)(HDMI2.0),but after entering the system boot, the resolution will be set to 3840x2160 (60Hz) normally.(with HDMI2.0 or DP)
Then I tried to connect HDMI to HDMI1.4 port,Display can display UEFI boot at 3840X2160 (30Hz) resolution,But you know, the 1.4 standard can only support 30Hz....