I went back to the old drivers. Without undervolt tools this has to be changed in Bios which is a pain and hard to edit on the fly. It will be worth it when the DAG becomes a bigger issue, but not right now.
It's really surprising how many people think this is great though. You should really undervolt...
I have undervolted my cards from bios as I have faced the issue like most people with latest driver. Reverting back to previous driver does not change anything. I still have 1 card functioning unstable. I am afraid it might be related to hardware issue