I just played around with my HD 3850 and realized that there is a bug in the bios for all first run 3850, 3870, and some 4xxx cards that causes the fan to stay at a certain speed all the time, mine never went above or below 47%, even though the bios chart says it should be much higher than that at the temps I was getting.
This bug has been fixed in the newer ones, but I suggest anyone who has one tests it. Just run GPU-Z and catalyst and test clocks in overdrive, if the fan speed doesn't change at all in GPU-Z it means you have a problem. Some people reported the sticker on the cooler falling off because the glue actualy melted.
There are a number of work arounds like using rivia tuner or some other tweaking program, but there is also a way to edit the bios yourself and put in a new temp/fan speed graph and switch graph modes to one that works. Which happens to be the recommended one in the program I used.
I just edited mine to go from 30% @ 30ºc to 100% @ 70ºc (and VOIDED THE WARANTY, unless I flash back to the old one :razz
It never gets to 70ºc now anyway.
I used TechPowerUp.com's RBE Radeon Bios Editor and used a boot disk with ATIflash and both bios files, old and new, just incase the new one didn't work. DON'T USE A WINDOWS BASED FLASHER! YOU WILL REGRET IT!
I'm not sure about mine, but some cards have three clock settings 2D, 3D low, and 3D high. Mine appearantly does, but they are all the same clocks in the stock bios, so I ignored them. If you do see different clocks, DON'T CHANGE THEM! It will just make the card generate more heat at idle, and has no effect on performance unless you experiance stuttering during switching from 2D to 3D, in which case, live with the stutter, its not worth the extra heat and power consumption. I woulden't suggest touching the clock settings at all even.
Flashing the bios isn't illegal, but I'm not sure if posting my edited Sapphire HD 3850 GDDR3 512mb bios is. Additionaly, this is the first time I have ever edited a bios, and other than fan speeds, its completely the same, including revision and dates. Infact, I doubt ATI would know the difference if you waranty or return the card.
There WAS a bios update offered from sapphire, but it required validating the card's Serial number and Part number, I don't know if it is still offered, but all it did was make the speed follow the original graph like it should. For me that wasn't enough, I wanted to set the graph for my temperature range because hitting 100% @ 105ºc is hardly ideal, and I didn't want to go through the trouble of signing up for the forums and locating the dev that has the fixed one.
If you do flash your card's bios, either with a fixed one, or a custom one, you need to know one thing. AGP cards have two device IDs in ATIflash. 0 is not the card, but a different chip, you need to flash ID 1.
Final note: don't ask me for help with using the programs I mentioned, if you can't figure it out you shouldent be using the program in the first place. Just Return the card and get the newest manufacture date available, it will have the fixed bios. I'm not calling anyone dumb, but you do need to know what you are doing. You also have to have the time to read alot, since you need to understand how the fan control works before you start changing all those crypticaly named variables.