I also have a GTX970 SuperClocked card and getting a issue where Despair Demons ( Cold Blasting ones) and Arcane Horrors cause my game to Crash to black screen or even BSOD. Has to be a driver issue or something in the spell effects or noise they make that triggers it. I have not tried underclock as of yet. Keeping a very far distances to fight them seems to be the only solution that has worked for me as of right now.
Also I do not feel I have a lower my Graphics settings or reduce down the speed of the card to be a fix. I want to enjoy the full spender of this game and should not have to do that to do so. I guess I am just stubborn that way.
