What is s3 sleep and how do I do it
S3 is a low power state. It might be a default in the bios. There are also some more and less aggressive states.
It keeps the ram alive in a low power state and turns most things off or down.
In the bios you might also see some options to allow certain events, like a keyboard to wake up.
You might turn off wake on lan event to stop unexpected wakes.
In ccontrol panel/power options/change advanced power settings/sleep
turn off allow hybrid sleep. That writes contents to a hard drive before going to sleep.
Also turn off hibernate after setting to never.