Not sure it's relevant in this thread or not, but my experiences with the Asus 4850:
I think at default (ootb) the fan must be almost non-existent. OOTB The idle temp was around 70-73, with load ramping it upto 85ish.
I installed the Asus software that it came with for controlling temps etc. As soon as it installed it pumped the fan to 100% (sounded like a hurricane) - the temp dropped fast to around 50c idle.
Then started changing all the settings for various fan levels. At 41% the fan is inaudible, holding idle at around 50ish. I changed the steps based on temps, so at 80c the fan hits around 65% - you can certainly hear it at that speed, but it does a good job keeping the temp down, with load temps avg 72 (max seen 80).
Now I've not played around with things like Rivatuner yet on this card, so I'm presuming you can get the fan speeds adjusted well with that. Likewise I'm not aware what utils are being distributed with the other brands/mfg's.
I'm gonna AS5 it at the weekend and see if they can come down some more.
Sorry for the boring post, but I've seen lots of posts about the temps on these cards ootb, thought I'd post my experience after a few days.
Cheers
Daz