Ok I have found a solution which maybe what the problem was with all the gigabyte cards... basically a bad overclock. I have now got an overclock with mine. Pics are attached...
As you can see I have bypassed the gigabyte overclock and everything is stable. Apps and games that would not run (3dmark11, bc2) now run perfectly fine and the card reaches a top temp of 78 degrees after half hour of stress testing with bc2 which slams the core at 99% and never drops.
I suggest cranking up the voltage because I honestly think that is the reason why the overclock that comes with the card is unstable. You can also see I have dropped the memory after cranking up the core..
Let me know how you get on...
Forgot to mention that Heaven still crashes but not because of a driver restart which indicates it is not the voltages or card but the actual driver...