Adjusting the speed of the HD 4850 & HD 4870 fan
Up to now it was not possible to control the fan of a HD 4850 or HD 4870, which gets annoying loud under heavy graphics workload. A post at Guru-3D-Forum explains how to do it.
To be able to get manual fan control for the HD 4850 and HD 4870 you have to proceed as follows: When a profile is created in the Catalyst Control Center with the integrated Overdrive, a xml-file is created. The "profilename.xml” is located in "C:\Users\Username\AppData\Local\ATI\ACE\”. You can edit it by right click on it. Set the value "FanSpeedAlgorithm value” to "Manual”, now you can set the speed of the fan with "Want value”, where you have to give value in percent.
<Property name="FanSpeedAlgorithm" value="Manual" />
<Property name="Want" value="0" />
<Property name="Want" value="65" />
Now save the file and load the profile. The profile has to be loaded at every system restart in order to override the default fan control.
In a short test the trick worked well with an HD 4850 and an HD 4870.
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