Fresh install of Fall creators update.
Download/unpack AMD drivers.
Shut machine down.
Install 3x Vega cards
Remove network cable
Boot machine and install drivers with no network connection.
Reboot machine
Go into crimson, enable HBC max.
Reboot
Connect ethernet
Begin mining XMR, 3,500h/s for 3x Vega 56x
Grrrrrrr
you don't need HBC turned on and set your pagefile as high as possible.