I had a chain #2 board fail after ~16hrs of use in a S7-B8 (was reporting 21 ASICs)
The unit was running default clock speed with a IBM 2880W PS. The temps were all
under 40°C prior to the failure.
The board has been shipped back for warranty (at my cost) and the responses from Bitmain
are that there won't be any compensation for the down time (failed Dec. 18) or my shipping costs. 

Is CGB 'stuck'?
I haven't had any change in confirmed / unconfirmed balances all day...

Well I'm hedging my bets as to which coin might or might not be best
by using  multipool. At least my GPU's still have some use there.
I doubt I'll ever have enough return from them to afford to get into
any high end mining gear, but who knows - maybe one of them will take off!