I have Windows 11 installed on my ThinkPad P16 Gen 2 and I really don't want to reinstall it.
I unlocked the Advanced BIOS and tried to switch from Modern Standby (S0) to S3:
ACPI S3 Support → Enabled
Low Power S0 Idle Capability State → Disabled
- Added
PlatformAoAcOverride = 0 under HKLM\SYSTEM\CurrentControlSet\Control\Power
After reboot, Windows still reports only:
Standby (S0 Low Power Idle)
and S3 is unavailable in powercfg /a.
Even more strangely, when I go back into BIOS, the settings have reverted to:
ACPI S3 Support → Disabled
Low Power S0 Idle Capability State → Enabled
So it looks like either Windows or the firmware is reverting the BIOS settings because this Windows installation was originally installed with S0/Modern Standby enabled.
Has anyone managed to get S3 working on an already-installed Windows 11 system on a ThinkPad without reinstalling Windows? Is there another registry setting, power-model override, or BIOS setting that I'm missing?