Microsoft engineer explains Windows' approach to CPU speeds

Windows can display two different CPU speeds in its System > About section. The first number comes from the processor brand string, provided by the manufacturer through CPUID function codes. The second is calculated by Windows itself. This discrepancy may help detect overclocking or misleading marketing claims. Microsoft recommends using Task Manager for more accurate CPU frequency information, showing both base speed and current performance. The difference highlights the complexity of modern CPU performance and how it's reported to users.