Definition of TDP according to Intel
Intel defines TDP in one of its white papers as follows: „The upper point of the thermal profile consists of the Thermal Design Power (TDP) and the associated Tcase¬ value. Thermal Design Power (TDP) should be used for processor thermal solution design targets. TDP is not the maximum power that the processor can dissipate.”
Tcase describes the temperature measurement via a thermocouple embedded in the middle of the heat spreader. The original measurement is made at the factory. After production, Tcase is calibrated by the BIOS system. For this, the measurement results are read on a diode between and under the cores. (Source: Intel)
According to Intel, TDP is a guideline, among other things, for the recommended heat dissipation. At the same time the Thermal Design Power says nothing about the maximum possible power output.
ComputerBase.de adds a further definition of Intel in one of their recent articles. According to this, TDP also stands for “the average power consumption (in watts) which the processor derives at base frequency when all cores are active in a highly complex workload, defined by Intel.” We can only speculate what exactly is meant by a “highly complex workload”.
However, what is clear from this definition is that the Thermal Design Power in no way depends on the turbo clock speeds of a processor. Since the Thermal Design Power refers specifically to the base clock of a CPU, could therefore not be deduced from how much power a processor rakes up during the day.
Definition of TDP according to AMD
Intel also mentions AMD's definition of Thermal Design Power in its whitepaper. AMD’s understanding of TDP: "The Thermal Design Power is the maximum power a processor can draw for a thermally significant period while running commercial software. The constraining conditions for TDP are specified in the notes in the thermal and power tables."
ComputerBase.de also lists another definition of AMD:
"The TDP is a strict measure of the thermal power dissipation of an ASIC (= Application-Specific Integrated Circuit) that defines the minimum cooling needed to achieve the specified performance."
Consequently, this would mean that a CPU can only achieve the intended performance as long as the performance is not throttled by too high a temperature.