I installed the BIOS mentioned in purecain's post (51) on my 3870 yesterday. I used Winflash 2.0.0.2 to do it and it worked perfectly.

The fan speed does seem to pick up more quickly than the stock BIOS, and obviously the standard clocks of the card are now faster. However, the card still hit over 90 degrees when using the Fur stress test so I force fan speed to 70% using Rivatuner when gaming. This is very loud but I drown it out with my speakers.

I'm at my parents house until the New Year now so can't test the card any further but I should have an Accelero S1 by then to help curb temps