I have firmware:735ccca5. I'm curious to see if anyone has a different version.
Same here 735ccca5
Mine is: ebaa1a85
I have not been able to get my BJ to run stable for over 48 hours. I need to hard reset it at least once a day. With each version of cgminer I have a different issue. The best one for me seems to be cgminer3.11.0hf1 but it seems to crap out at random intervals where mining stops and I am unable to ssh or load the web interface anymore. Hopefully new a firmware/cgminer combo will fix these issues as my warranty already has expired :/
Also there is a 7 degree difference between cores, so I might take Phil's advice and re-apply thermal paste. (Although the hottest core does not exceed 80C, so I don't think overheating is the cause if my instability issues)
It might not have anything to do with your situation but I have had problems with Hashfast devices disconnecting from cgminer if the internet connection is disrupted. They would try to return but on the two occasions this has happened I had to power cycle everything to get it going again.