I would also recommend the following if your hash rate is fluctuating wildly using automatic settings, it definitely stabilized my rate!
Ok there is 16 factory overclocked board. I think PSU can't handle that much.
First set speed on all boards to 52
Login to Pi and do command
rm /opt/bitfury/best.cnf ; for i in {1..256} ; do echo -e "$i\taIfDSo\t52" >> /opt/bitfury/best.cnf ; done
1 - After that try run with 12 boards for test for 30 min.
2 - If no hash drop, shutdown miner and add 1 more board.
3 - Make test.
Repeat for max board count working stable.
I strongly suggest decrease voltage on all boards. Turn little pot near Pulse inductor on Hboards counterclockwise about a quarter turn or so.