Just orded a gtx 670 everyone. I will update this thread with my impressions. I will be replacing my 5770.
I'm on 10.6.8, but my fans are currently:
Booster 1 - 709rpm
Exhaust - 496rpm
Exp slots - 1518rpm
Intake - 497rpm
Pwr sup - 944rpm
Dunno... I'm using a 5870 from Apple, though.
I also have an Areca RAID card in there, and an app called Fan Control in use.