I have 1000 Avalon 741s running in batches of 20 with no issues. I wonder if the 8 introduced some kind of instability?
Make sure you have at least a 2.5 amp power source for your RPi, underpowering them leads to AUC crashes and other issues.
thanks, I am running the official Rasberry adapters with the Pi3s just to ensure power wasn't an issue as I read in general about Pi instability with under powered adapters. I don't know if there is any instability but just fishing for possibilities. The other user here said that he had reduced hash and instability running a full controller but it may just be a YMMV kind of deal. I am also running the latest controller and firmware.