I just recently reinstalled Windows 10 Pro and initially everything worked properly. However, the S3 Standby is not available anymore. Running powercfg /a gives:
C:\WINDOWS\system32>powercfg /a
The following sleep states are available on this system:
Hibernate
The following sleep states are not available on this system:
Standby (S1)
The system firmware does not support this standby state.
Standby (S2)
The system firmware does not support this standby state.
Standby (S3)
The system firmware does not support this standby state.
Standby (S0 Low Power Idle)
The system firmware does not support this standby state.
Hybrid Sleep
Standby (S3) is not available.
The hypervisor does not support this standby state.
Fast Startup
This action is disabled in the current system policy.
I already reset my BIOS settings and changed my group policies as in this post. I also updated my graphics drivers and installed the latest AMD chipset driver. I have a MSI x370 Gaming Pro Carbon motherboard and a Ryzen 1700.
Edit
I managed to fix it enabling SMT. Seemingly S3 Standby is not available if SMT is deactivated.
