with the new firmware bitmain has limited the frequency, balance: 500mhz turbo: 550mhz. is it possible to change the firmware to have 700/750 mhz?
The unlocked firmware I have available does allow you to set any frequency, but the webUI allows you to go to 650Mhz.
Past 650, I've found that the Z9s limit current/voltage, but it depends on the machine as to where the line is.
-j