Question on Proof of Stake Computing Power

Hello guys and gals, I have a question about where exactly the processing power for proof of stake networks comes from. I understand that there is a lot less processing power required for proof of stake systems, however, I understand that it is nonetheless required. Now that there will not be any miners to provide that, where will it come from? I understand that people supply their crypto through staking in order to create a node, but who actually supplies the processing power "behind the scenes"?