When overclocking the 3rd generaiton Intel® Core™ processors do run hotter but at their normal speeds they they are cool running processors. In the end I have tried to keep the temperatures on my overclocked Intel® Core™ i5-3570K under 80°C when running Prime95.
I have mine at 4.2ghz running at about 34-41c at 70% +-
Thermal Radar is just a set of temperature sensors on the motherboard. The CPU's on-die temperature sensors will be much hotter since they are directly inside heat source, cutting out all the heat flow resistance and dispersion.