Well as we all know not all chips are created equal.
But have got it sorted out now, but took a while.
I believe new firmware might use a little more juice.
But I'm tuned now:
0.45Th/s 231.25Hz 0.76v
0.467Th/s 231.25Mz 0.755v
0.465Th/s 237.5Mz 0.765v
Which gives me a very nice 0.76W/Ghs (A little bit higher for my PSU), so I am much happier, and does seem stable. But it took a lots of Frequency, Voltage tuning, and voltage made a real difference +/-0.05v.