Do you know with a 750 the miner is slower than 700 ?
when I set up Z9 mini at 700 I get 15.5 Kh/s while at 750 14.5 Kh/s !
This is not correct. You need to be looking at the average hashrate taken over a long period of time, I assume you are either looking at the current hashrate (it fluctuates quite a bit) or not giving enough time to calculate an accurate average.
my average at 750 is 16.95 Ksols/s over the past 24 hours. Sometimes into the 17s