Microprocessors have a maximum TDP they are designed to work within. This essentially should encompass both power and heat. When not utilizing every core available in a modern processor, there is "room to spare" in the TDP maximum. CPUs that have a boost function, will increase the frequency of some of their cores to various boost states, while maintaining compliance in their power and heat envelopes, allowing some tasks to complete sooner than they otherwise would have.
While you could disable the boost states, and also power management on your CPU, the benefits are not always there. When turbo is functioning normally, it is essentially clocking up your processor in a stable manner, similar to what you would achieve through overclocking, but it will also dial back processor speeds as the computer sits idle, saving on electricity costs and generating less heat. Overclocking manually can become very inefficient as often times power management functions are turned off to achieve stable overclock results.