Just one card need monitor or dummy(hdmi->vha adapter as the card only have digital output)
you disabled problem is something of different problem
you disabled problem is something of different problem
you may have to disable UPLS (low power mode that disables 2nd gpu when not in use), you can do so in MSI afterburner or amd options i think. also disable crossfire.
I don't have the option for Crossfire, and "disable ULPS" is ticked in MSI AB.
It seems to be mining, but very slowly.
Edit: Both rigs are running win 10 x64, Crimson 16.6. I'll try installing 16.9.2.
Edit #2: Updating drivers didn't change anything.