WOW !
This one works !
Previously I had around a miserable 300 Gh/s (and more than 10% cores disabled) as well as more than 30% HW-errors.

But look now:  524 Gh/s (avg in the last 27 minutes). and only 6.5% HW-errors.....  And I just looked at the cores: only 9 of the 768 cores are disabled.   And BitMinter-pool is even telling me that I'm running 591 Gh/s !!!  

I didn't believe this could be solved with software-update. But they did!   Congratulations KnC !