The only things i can think off is that the Monitor cables should not be longer than 3 meters and not active (only use active cables when 5 meters or longer.
Sometimes Bios update for the mainboard (i know it sounds weird) and or Graphics Card does help.
I did hear the “Sleep issue” before, something like the MST Hub needed a new power cycle before being able to communicate again … What firmware version i on the CSV-5300H ?