Also AMD doesn't cheat on TDP much. When they list TDP. That means TDP under full load. Intel has been getting much worse about this with Coffee Lake.
For example
Ryzen 2700x rated TDP 105W actual torture loop 104.7W
Intel i7-8700K rated TDP 95W actual torture loop 159.5W
Intel i7-9900K rated TDP 95W actual torture loop 204.6W
https://www.tomshardware.com/reviews/intel-core-i9-9900k-9th-gen-cpu,5847-11.html
So, yes Apple's cooling is withing spec. Except Intel's spec sheet is way off. They are claiming the same TDP as an i7-7700K. Which the iMac was fine with. Except actual power usage (heat generation) under full load has nearly doubled.
If AMD holds true to form. Their Ryzen 3900X will hit a maximum Turbo Core of 4.6Ghz (don't know multi-core max). But 12 cores will do max Turbo Core within 105W. With a better IPC than Intel (performance per Ghz). Come on Apple. Dump Intel. At least for the iMac and Mac Mini. I mean you already love AMD GPUs. Give their CPUs a shot. If you did this with the Mac Pro and Zen 2 Epyc it would have more PCIe lanes, PCIe 4.0 and 64 cores.
TDP has never been peak power consumption. Technically its not consumption at all its a energy measurement in watts of heat dissipation that is averaged (because they are two different metrics) at base clock.
Below is out of the i8 or i9 data sheet from intel.
The CPU's have TDP # the same as their PL1 numbers IE base clock. When you start a task PL2 is the limit of power consumption. In the case of the bottom CPU 4-Core GT2/GT0 that would be ~81W of power consumption (65W x 1.25 = 81.25W). In quick task this isn't an issue as 1 core will boost up well into turbo range but since its only a single core it won't exceed 81w of the package design. However if the load gets heavier and more cores are used and 81w of power is exceeded for more than PL1 Tau (8 seconds) the PL1 will be set as the limit.
Here is where this gets interesting. PL1, PL2 and Tau are adjustable by the manufacturer or overclockers which adds all sorts of variables.
With that in mind here is a screen grab from the OP's video.
Notice the temp spiked to
119-120w held for a few seconds and dropped to below 90w? That is a 95w CPU (95w x 1.25=
118.75w) aka PL2 held for a few seconds and dropped to PL1. PL1 has been lowered because if you watch the temps they keep creeping up but level out before 100c.
So the OP is right and wrong, the CPU performance is being limited because it
would get too hot not because it
is getting too hot. Aka its an artificial limit to keep from hitting tjunction max.
The opposite applies too if you had a REALLY good cooling solution and set PL1 to and PL2 to 150w then that is the kind of power consumption you'll see as long as thermal limits aren't hit.
Intel even goes as far as explicitly saying that your cooler should be designed for the heat dissipation at PL1 (TDP) as the minimum.
Peak power consumption can only be defined by the company/person buying it (unlocked) which is why Intel doesn't give that spec. Intel just gives you an average based on their stable base clock designed for longevity.
