Had more time to play around with these miners. Basically the ASIC CHIP cannot run at all under 0.70 Volts. I tried 0.67 Volts and its impossible to make it run under any frequency without getting huge hardware errors. 0.70-.71 Volts is the limit on these chips.
I have managed to get it to run on 181Mhz frequency and its very stable, no "X", and gets like 0.004% hardware errors. It hashes around 915Gh/s and uses around 830Watts of power at the wall. So 0.90Ghs/W and the stock would of been 1.1Ghs/W using the same hashrate.
Runs cooler and will pro-long the life of the stock Enermax 1000W PSU.
Sorry for writing to that almost three years later...
But what is the hex value for 181MHz? And what timeout did you use? ("bitmain-freq" : „40:175:0681“,)
thanks in advance
freeapp