My keyboard and mouse turn my PC on when PC is off.

dalchina said:

You said 'mouse movements don't turn it on' ....

I was assuming you meant 'press a button' - a power switch...

Oh, you mean you move your mouse and your switched off PC doesn't respond, but you press a mouse button and it does. Sorry, I misread your description.

So it must be in a sleep state.

Try turning off Fast Startup.
Turn On or Off Fast Startup in Windows 10 Windows 10 Performance Maintenance Tutorials

If you are interested, you can check what state it booted from thus:
Check if Last Boot from Hybrid, Full, or Hibernate in Windows 8 and 10 Windows 10 Performance Maintenance Tutorials

Fast Boot does what the title says it does - allows the PC to boot faster. Not sure how that ties into the OP's issue of wanting to stop the PC from starting with mouse or keyboard clicks.

Same goes for Fast Startup, which allows to PC to start faster after shutdown. Not sure how that ties in either. They've nothing to do with the OP's issue.

McSweg said:

Razer Blackwidow v2
Razer Mamba TE

when my pc is fully off. i can turn my pc on by pressing a keyboard button or clicking on my mouse.

How do I stop that? I only want it to turn on from my PCs power button.

Regardless, their issue is not a sleep state. And does not have anything to do with Fast Startup or Fast Boot. Anyway I provided a possible solution to the OP but it seems to have been ignored.

Peace

The idea came from something I read, not from any logical thinking. A stab in the dark.

Let them follow your idea.