That is great power usage.
I am wondering why we cannot change the power limit in a similar way we do on the nvidia rigs as on the amd rigs? I also am drawing 950-1000 watts for 6 x 570 4gb rigs and would love to bring that power consumption down so I can add more rigs in my basement XD
My 6 cards(AMD) are doing 800-900w range at the wall under 1000w on my 7 card AMD rigs. Have you tried 1050/2000 @ setting #2? That seems to be the lowest voltage for me, for some reason setting 1 pulls a very small amount more power 10-15w for the whole rig. 1050-->1100 is like 50-75w whole rig. Also I'm running 7th gen pentiums or 7th gen celerons, I think this saves a few watts, still 7 risers and cards under 1000w should be possible.