ok Alex I tried ... Good results even without overclocking the mems too much ...
But it remains to be seen why half cards go at 35mh and half go at 28mh / s ...
I will disassemble 2 boards to compare the pcb to find any differences ..
Try to rewrite bios 8gb on the half slow.. maybe you forgot to remove protection For every card with nvflash64 --protectoff ? I had a card that apparently had been flashed but I forgot to remove the protection and went into zombie mode
Alex