I see that the coreclock of your gpus are all different. It's probobly because they trottle. Not enough power or too much heat. You can increase the templimit, but not sure if this is the problem.
The old series 1070 can be bought this much mhs. I was able to reach 26.5 mhs (old miner 24.5). If I increase the power, maybe it will be 28 mhs, but I am in a country with high electricity prices. Thank you very much for your help. Compared to other miners, there was a total increase of about 200 mhs in my system with the same power operation.