Which version of Everest?
What do the latest versions of Real Temp and Core Temp report the temperatures as being?
The top of the thermal range for a G0 SLACR cpu is 71°C so 66°C is within the "safe" range, I wouldn't be overly worried about it tbh.
What are you using to stress your cpu?
Is it a G0 or a B3?
What Vcore are you feeding it?
Which cooler do you have?
Lots of variables to consider