|" displaying the CPU is 100%"|
Are you talking system idle processes?
You need to differenciate between a overheating issue and that of a malware infection. You are making them the same thing like malware is making your cpu run hot. Doesn't work that way.
You can run your car at idle or at 100mph, and if everything is working as designed, your temp will remain within normal params.
BTW malware is always found in memory. That is how it can operate. Doesn't do damage if it just remains a registry hack or a file on the disk.
Try malwarebytes to scan for malware. I have found it to be better than Spybot.