There is no video signal before loading the OS, it is impossible to go into UEFI with Vega family cards, polaris via DisplayPort on a monitor with an aspect ratio of 21:9 and 100 Hz
Please do not offer to use HDMI
Monitor: C34H89 -> DisplayPort
GPU:RX Vega56(Asus AREZ STRIX, MSI AIR BOOST), RX 590
CPU:1700x MB:Asus x370-Pro, AGESA PinnaclePi 18.104.22.168
On nvidia GPU, this problem was not observed
Maybe someone came across this?
Thanks for attention