I run with 2 cubes without problems (nearly zero rejects, nearly zero hardware errors, and 155 Mh/s). But two faulty cubes. one gives that error above, the other gives "failed to set workstate" and both dump BGFminer within a few minutes.
Elenelen, do either of your 2 faulty cubes work ok when used alone on the controller ?
No they don't. But the controller has it's own issues: if 4 Cubes are connected then you cannot open the Advanced-page anymore, because it times out (after 50 seconds). If 3 cubes are connected the advanced-page pops up after 30 seconds.