By default the USB polling interval is once every millisecond (ms). Even if no USB devices are connected the polling operation is still performed and the processor may not be able to enter power-saving state. Use this tweak to increase the polling interval.
Open your registry and find the key below for your Windows version.
Windows 98 and Windows Millennium Edition
[HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Class\Usb\0000]
Windows 2000 and Windows XP
[HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Class\{36FC9E60-C465-11CF-8056-444553540000}\0000]
Create a new DWORD value called “IdleEnable” and set it to “1” to enable USB idling and increase the polling interval.
Restart Windows for the change to take effect.
Note: This tweak should resolve the issue of laptop computers unable to enter the C3 processor power-saving state. By increasing the USB polling interval from one ms to five ms the processor can enter a C3 power-saving state during its inactivity and extend the battery life of the computer.
[REGISTRY SETTINGS]
System Key: [HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Class\Usb\0000]
Value Name: IdleEnable
Data Type: REG_DWORD (DWORD Value)
Value Data: (0 = default, 1 = enable idle)
PS: Works For Windows98/Me/2000/XP 
This is Shailendra,a part time blogger from India.
