I recently went through my own battle with this monster.  Have you tried rolling back the software? Like Openminer V1.2.0?  I have a zip file if you need it, My B8 is on 1.2.0 and is currently hashing at 52TH/s.  I have heard bitfury was working on a new firmware that could push the B8 into Tardis territory (68TH/s) but I am not sure if I trust my source (salesman, HAHA)