I just removed my shitty ass cooling contraption from my BFG 6800GT (the kind with the 2 small fans), and put a new NV Silencer 5 on. It was a little nerve racking removing it from such an expensive piece of hardware (and voiding the warranty to boot).
I did it because my temps were way to high IMO. Idle was hovering around 54C and load was getting up to around 85C! So I applied my thermal goo to my memory and GPU and tested it out.
*Idle of 54C went to 42C
*Load of 85C went down to 68C!
I must have had some bad contact with the stock heatsink, but I am much happier now that I can achieve a more stable overclock. Not to mention how much quieter it became.
How hot does your GPU get?