Running 2.8c now, One of my GPU's still drops to 0.0mh.  I have two models of this card, same memory, both with stable overclock.  Runs fine with 2.7b.  Have tried to lower significantly its memory clock from 2200 to 2100, 2075 and 2050, does not fix the problem, left the core at 1150.  With version 2.8c I have tried to use the -clnew 0 flag for that particular GPU while designating the other cards in the system -clnew 1 yet it does not fix the problem.  I run the card with -mi 12 on 2.7b so I also tried to lower that to -mi 10 on 2.8c with no difference in result.  Only way that card remains hashing is by running it separately with 2.7b.  I have also tried claymore 11.6 version with the same conclusion, hashes for a minute or two and drops out to 0.0mh. 

Has anyone else experienced this particular problem?  Its not a major issue for me running two versions but it is the idea that I cannot solve this problem has me twisted atm.