^^mine is a sapphire 4850. Since my OS is WinXP SP2, i can tell you the step by step procedure for this OS only. After you have installed the card and then installed Catalyst drivers, open the Catalyst Control Center, go on ATI overdrive, enable ATI overdrive. On the top there is an option called Profiles, click on it and open profiles manager and create a new profile by typing any name then select the radio button option all Catalyst Control Center Settings and save that profile. Open My Computer and Click on tools and then folder options. Select the View tab and select the show hidden files and folders radio button. After that open the partition on which you have installed your OS. Mine is D, so the path i followed is D:\Documents and Settings\Administrator\Local Settings\Application Data\ATI\ACE\Profiles, once you are inside that folder you can view the profile by the name you saved it with. It would be an XML document, right click on it and select edit, it will open in notepad, find and edit the following which are in BOLD only:
</Feature>
<Feature name="FanSpeedProtocol_0">
<Property name="FanSpeedProtocolProperty" value="Percent" />
</Feature>
<Feature name="FanSpeedAlgorithm_0">
<Property name="FanSpeedAlgorithm" value="Manual" />
</Feature>
<Feature name="FanSpeedRPMTarget_0">
<Property name="Want" value="0" />
</Feature>
<Feature name="FanSpeedPercentTarget_0">
<Property name="Want" value="45" />
</Feature>
After that save it and activate the profile in CCC and you will get the manual fan speed activated.