It is important to mention that is considered as overheating when the processor temperature reaches 95C or more. After the 100C the processor will turn off the system as a security feature.
The normal load of the processor will have the processor between the 40 and 65C and when running a task it can reach the 77C.
Based on your description, it seems that the temperature your system is getting Is normal. However, I would recommend you the following:
- Make sure there is enough air flow inside the case.
- Renew the processor thermal paste.
- Take the board outside of the chassis for testing purposes.
- Update the bios in your system.
- Make sure the CPU fan is connected to the CPU header and not the rear header.