Running @ difficulty 2048 - discoverd that vardif pool ports are bad for my units - if for some reason they drop under 300 -- they will not recover - stop hashing... Happened all the time on the BE Controller; & initially when I went to the Minera RPi image -- haven't switch back to a vardif port since -- pool I mine doesn't have ability to set difficulty.
Try setting the difficulty to a static number if you have not done that already, 1024 seemed to work OK for me on Ghash.io.
What is your hash rate @ 210?
I haven't gone past 210. Might just keep it. That way.
1225Gh. I have a cooling duct aimed right at them.
I down clocked to 230 - earlier today (about 5 hrs ago) - and added a fan (at 4:05pm on the graph below) blowing on the side of the 2 prismas - wide variance in poolside hashrate - seems better the last hour with fan and clock 230 - Minera Error/Reject Rate @ 3.84
http://i.imgur.com/w729eeT.png