When Windows Server 2003 starts, the speed of the one initialized processor is determined by the CPUID instruction, and stored in the registry.

When you use mixed speed processors in Windows Server 2003, all processors run at the speed of the slowest processor, so the stored frequency can be incorrect.

Some tools, like Device Manager, use the speed stored in the registry.

Other tools, like MSInfo32.exe and DXDiag.exe test each processor for current processor speed.