The bad news is that even the latest BIOS (S2895) does not include any settings for power-management.
The good news is that the board supports ACPI 2.0, so you should be able to configure it in software to use S3.
If you are using Windows, you can download Microsoft’s dumppo utility and disable S1 as so (from an admin command-prompt):
dumppo admin /ac minsleep=s3
Reboot, and Windows should only use S3 instead of S1 from that point on.
If the BIOS is reporting that it does not support S3, check that all of the necessary power cables are plugged in and that the power-supply is compatible. The K8WE has specific power requirements and perhaps it is preventing STR if they are not being met. From page 32 of the manual:
There are three power connectors on your Thunder K8WE.
The Thunder K8WE requires an EPS12V/SSI EEB 3.51 (24 pin + 8 pin) power
supply to boot. TYAN recommends using a split plane power supply because of
the amount of power the S2895 requires.
You also have an option of using an SSI v3.51 workstation power supply. This
is recommended when running both PCI Express slots.
WARNING: NEVER plug the 8-pin power connector into the 6-pin
connector. Doing so will damage the motherboard and/or
other components.
Please be aware that ATX 2.x and ATXGES power supplies are not compatible
with the board and can damage the motherboard and/or CPU(s).
This chart represents SSI EEB 3.51 split plane power supply.
…
Applying power to the board
- Connect the SSI Workstation 6-pin power connector (if needed).
- Connect the 8-pin CPU Power connector.
- Connect the 24-pin Main Power connector.
- Connect power cable to power supply and power outlet
NOTE: YOU MUST unplug the power supply before plugging the
power cables to motherboard connectors.