I have a six 470 rig, modded BIOS with Claymore 11.2 and the following config:

-dcri 1
-cclock 1240
-mclock 2200
-cvddc 950
-tt 72
-fanmin 50
-fanmax 90
 
Does anyone know why I'm getting about 27MH/s for the 5 GPUs and 32MH/s for 1 of them?
The GPUs are identical and bought on the same batch.