The active bus polling that is required to maintain communications with USB devices can prevent the CPU from switching to a C3 power-saving state.

The default polling interval for USB devices is one millisecond, which may interfere with the ability to enter a C3 power-saving state.

NOTE: This problem can exist even if no devices are connected to the USB controller.

To resolve the issue:

1. Use Regedt32 to navigate to HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Class\\{36FC9E60-C465-11CF-8056-444553540000\}\0000.

2. Edit or Add Value name IdleEnable, a REG_DWORD data type. Set the data value to a number between 2 - 5 milliseconds.

3. If additional subkey exists (\001, \002, etc.), repeat step 2 for each subkey.