I have taken some shared soft PP reg file with 1408/1050 clocks and only lowered the GPU clock.
Settings:
GPU_P0=852;900
GPU_P1=991;900
GPU_P2=1084;900
GPU_P3=1138;900
GPU_P4=1150;900
GPU_P5=1202;900
GPU_P6=1212;905
GPU_P7=1340;905
Mem_P0=167;900
Mem_P1=500;900
Mem_P2=800;900
Mem_P3=1050;900
Fan_Min=10
Fan_Max=4900
Fan_Target=60
Fan_Acoustic=2400
Power_Temp=85
Power_Target=0

So my cards consume about 250W each with 1.8Mh/s hashrate, profit/consumption ratio is not really good.