Unfortunately my 6950 is running at 85 degrees atm =(
It doesn't look like ill be overclocking any time soon.
If you underclock the memory (not needed for BTC hashing) it greatly reduces the temperature. You'll have to do some research and then experiment yourself. For instance my card's stock clocks are 850 MHz GPU and 1200MHz memory. I currently run 960/300 and my temp is around 70-75C. By reducing the RAM speed you can run higher GPU speeds for the same or lower temperature.
You definitely don't want to run at 85C for any length of time. At least aim for less than 80C.
Also, is your 6950 plugged into your motherboard or in an external rack? If it's on your motherboard, leave your PC's case open. This *greatly* improves airflow and reduces temperature. This is what I do. I leave the side panel off my PC all the time now.