Win XP in S3 Sleep Mode

If you installed Windows XP before enabling suspend to ram in your BIOS, your computer may be limited to the S1 system power state, instead of the deeper S3 system power state.

To resolve this problem:

1. Download the undocumented Microsoft dumppo.exe utility and save it in a folder that is in your PATH.

2. Open a CMD.EXE window.

3. To determine your Min sleep state and Max sleep state, type dumppo.exe admin and press Enter. You will receive a display similar to:

Admin policy overrides
Min sleep state......: S1
Max sleep state......: S4 - hibernate
Min video timeout....: 0
Max video timeout....: -1
Min spindown timeout.: 0
Max spindown timeout.: -1

 4. To set the Min sleep state to S3 and the Max sleep state to S4, 

type dumppo.exe admin minsleep=s3 maxsleep=s4 and press Enter

NOTE: Dumppo.exe configures the PolicyOverrides Value Name, a REG_BINARY data type, at HKEY_LOCAL_MACHINE\system\currentcontrolset\control\session manager\power.
After typing dumppo.exe admin minsleep=s3 maxsleep=s4, my PolicyOverrides contained 040000000500000000000000FFFFFFFF00000000FFFFFFFF.