If you processor supports Intel SpeedStep or AMD PowerNow, you can configure processor performance via the registry:
1. Navigate to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\P3\Parameters.
2. Edit or add a HackFlags Value Name, a REG_DWORD data type, and set the data value to one of the following:
0 Disable native Windows XP support.
1 Use settings inherited from Intel software during your Windows XP upgrade.
5 Windows XP should support all modes when running on battery.
3. Exit the Registry Editor.
4. Shutdown and restart your computer for the settings to take effect.