identify the location of the process that's using all the cpu, and it's services Kill the process. run malwarebytes to identify any other suspicious things then go to the location and delete it. ...T
"Spikes" generally means it goes up for a very short period of time. How long is your spike duration? If it's very short and random it just may be Windows being Windows. Are these spikes affecting performance? What do you have running in background? Try elimination what you don't need. We all have our favorites, but I have a firewall and AV set to run at startup. Everything else is on demand. Are you by chance looking at the System Idle process?
I've noticed that svchosts.exe will spike your cpu when windows is attempting to update your pc, Check windows update first and then update to see if that helps