Atta boy.
This stuff will knock 3-5c off load temps.
http://www.overclockers.co.uk/showproduct.php?prodid=TH-001-GD
Have you put that on your cards?
I forgot to say that one of my cards has Elipda memory, and the other has Hynix. Makes no difference to me though. I haven't had any black screen issues, and the cards now run great after I reinstalled the 13.12 drivers yesterday (DDU for the win!).