I'm getting 31.6 MH/s steady on 4 cards with ethOS.

Sapphire Nitro+ 4GB

core = 1280
mem = 2200
powertune = 7
miner = claymore
voltage = 0.7

My problem is I need another power cable from my PSU for the risers on the 5th and 6th cards. Hopefully it'll arrive soon!