My 470 stock idle in a closed SilverStone case with all system fans on low.
I tried 2 hours of Crysis all VH @ 1920x1200 stock last night to establish a baseline for temps. In a closed case with system fans on low and the GPU fan @ auto I hit 85C. The fan went up to 53%. Tonight I am going to run my OC with 65% fan speed set manually and see what happens. This weekend the stock TIM is going to be replaced with Shin-etsu. Usually the factory applies too much and uses a rather standard grade.
The GTX 470s fan is loud at high levels and I haven't had use it @ that level yet.