I have mixed rig here: 4*470*4GB (3*Sapphire refs and 1*Asus Strix) and 1*480*8G (MSI ref) all on raisers.
1) all flashed with tighter timings from 1500
2) memory and core set to 0.857v
3) all mem runs @ 2000MHz
4) 480 drives display (do note that if you try to stick display in any of 470s - you'd need to increase the voltages, otherwise won't even start mining)
5) using watttool to push mem voltage
6) only the drivers from 16.9.1. No wattman gui - it feels more stable to me this way.
Using claymore dual, each 470 gives 28.3MH and 480 does 29.1MH, total power off the wall is 825W:
P.S. same results on B150 Pro4/D3