Q. How can I enable the S3 system power state for standby when USB devices are armed for wake?

Windows XP and Windows Server 2003 enter the S1 system power state for standby, and only enter the deeper, power saving, S3 system power state if no USB device is armed for wake.

This behavior occurs because too many computer BIOS report that they support the S3 system power state for their on-board USB host controller, when they really don't provide proper support. When these systems attempt to wake from the S3 system power state, you can experience loss of power, false device removal/arrival notification, reset of attached USB devices, failure to resume, and other undesirable effects.

If you know your computer supports the S3 system power state for standby when USB devices are armed for wake, you can arm the device by checking the Allow this device to bring the computer out of standby on the Power Management property dialog in Device Manager.

To enable your computer to enter the S3 system power state when USB devices are armed for wake:

1. Open a CMD.EXE window.

2. Type the following command and press Enter.

reg ADD HKLMSYSTEMCurrentControlSetServicesusb /v USBBIOSx /t REG_DWORD /d 00000000 /f

NOTE: Installing a 3rd party USB host controller when the USBBIOSx Value Name exists may cause problems waking the computer through the 3rd party controller.

NOTE: Microsoft does NOT recommend adding this key and Value Name.