Mobo: ASRock H81 PRO BTC R2.0 S1150 Intel H81
GPU's: 6x Sapphire RX570 Nitro+ 8GB
I never had any problems booting the system before as I was setting the rig up whilst the screen was always plugged in and now when everything is set up I must plug the monitor in to boot the system. Never ever had this kind of problem with any other computer systems.
What happens if you boot up the system with a monitor installed and later, when mining has started, you just take out the monitors power cord from the outlet?
I use my rig that way and if I need to do something with it I use Team Viewer from my phone or laptop.