USB mouse wake up

Does any1 know if USB mouse can wake up system that is power down ( shut down) already?
From BIOS I can only see settings for mouse wake up on S3 which is suspend to RMA. Pls advise how can I set my mouse to boot up my system.

Does anyone knows why is there USB bus power even though the PC is already shut down? What is the function?

It totally depends on your hardware and BIOS version. Some can do it, some surely don’t.

Check your BIOS if there’s a wake-up on event option (usually located in the power management menu) and see if it can be toggled to a USB mouse. Also, you might have to enable USB mouse support in your BIOS (yes I know that a USB mouse can work fine in Windows, even without the support for the USB mouse enabled). If such an option isn’t listed, you might have to update your BIOS. Check the changelogs for your mainboard’s BIOS file to see if such a feature is added.