Is there some sample code for Windows XP or 7 for getting and setting the speed on a FirePro V7900?
are you looking for a way to read/write the gpu clocks? If so, ADL provide the functions to do this. But on FirePro it will not allow you to change the engine/memory clocks. So you can only read them.
ADL is available on the AMD web site: http://developer.amd.com/sdks/adlsdk/pages/default.aspx
The function to read the clocks is: ADL_Overdrive5_ODParameters_Get