already had a monitor on it, same rig with windows 10 no issues.
tried it with a X session on the monitor and without.
no difference.
and it's always gpu0
enabled the onboard intel graphics to use with the monitor so that no screen was attached to any of the cards, same issue
if i swap cards around it's always gpu0 with the crappy hashrate, seems like it never goes to mode 7 even when putting the card in manual mode and setting mode 7, it doesn't take.
and what ever i do to over or underclock, i always get this message in dmesg:
VDDCI is larger than max VDDCI in VDDCI Voltage Table!
tried with drivers 16.40 till 16.60
I had the exact same problem where a GPU got stuck in a lower power state which caused that 4 MH/s bug on a 6x 470 rig operating Windows 10 just a few hours ago. I solved the problem by simply connecting a screen to that particular GPU. If that doesn't do the trick, try connecting to any other random GPU.