Electronic device and clock rates controlling method of overclocking operation

An electronic device, comprising:

• a central processing unit (CPU) used for over clocking operating;
• a temperature sensing element coupled with the central processing unit and used for sensing a temperature of the central processing unit operated in an over-clocked state wherein a clock rate of the over-clocked state is higher than a normal clock rate;
• and
• a control circuit coupled with the temperature sensing element and the central processing unit and configured to control the central processing unit to enter an idle mode when the temperature of the central processing unit operated in the over-clocked state is higher than a first threshold temperature,
• wherein the control circuit is further configured to control the control processing unit to return to a normal mode when the central processing unit is at the idle mode and the temperature of the central processing unit is lower than a second threshold temperature,
• wherein the first threshold temperature is higher than the second threshold temperature, and a clock rate of the central processing unit at the idle mode is the clock rate of the over-clocked state and equal to a clock rate of the central processing unit at the normal mode.