Here is a good place to start reading on it:http://www.intel.com/content/www/us/en/architecture-and-technology/turbo-boost/turbo-boost-technology.html
"Intel Turbo Boost Technology 2.0 is activated when the Operating System (OS) requests the highest processor performance state (P0).
The maximum frequency of Intel Turbo Boost Technology 2.0 is dependent on the number of active cores. The amount of time the processor spends in the Intel Turbo Boost Technology 2.0 state depends on the workload and operating environment.
Any of the following can set the upper limit of Intel Turbo Boost Technology 2.0 on a given workload:
-Number of active cores
-Estimated current consumption
-Estimated power consumption
When the processor is operating below these limits and the user's workload demands additional performance, the processor frequency will dynamically increase until the upper limit of frequency is reached. Intel Turbo Boost Technology 2.0 has multiple algorithms operating in parallel to manage current, power, and temperature to maximize performance and energy efficiency.
Note: Intel Turbo Boost Technology 2.0 allows the processor to operate at a power level that is higher than its rated upper power limit (TDP) for short durations to maximize performance."