Cpu temperature protection(Thermal Monitoring Technologies).

[basics]

So novadays most cpus have a high temperature protection that decreases voltage in order to decrease cpu power in order to lower the temperature. We can find out the maximum temperature supported by a cpu (tcase) but what is the temperature at which the protection system(Thermal Monitoring Technologies for intel) comes alive? How do i find that out? Ty

 

[aznricepuff]

"Tcase" (technically Tcase_max) is actually the maximum expected temperature at the CPU's integrated heat spreader when the CPU is running at 100% load at its thermal design power (TDP).

Tcase is not the maximum tolerated core temperature (what on-die thermal sensors actually report). In fact the temperature of the heat spreader is almost impossible to practically measure during normal operation. Moreover temperatures at the heat spreader are generally lower than temperatures at the CPU cores (in fact if they aren't your CPU is about to end up fried - just think about basic principles of heat flow). Finally, if you read the definition of Tcase you'll realize that it is not some hard upper limit; it is just an estimated value of how hot the heat spreader should ever get.

Intel FAQ explaining Tcase and Tjmax.

EDIT:
I just did some more research because I was curious and it turns out that the situation is a bit more complicated than what I typed above, so I'd like to make some clarifications.

First, you should completely ignore Tcase. Everything I say about it above is true, but knowing what Tcase is and what the specs are for particular CPUs will do you exactly zero good. Like I said you can't even measure it normally (you'd have to manually drill a hole into the heat spreader and stick a thermocouple in there). Moreover it is not that important to you, the end user. It is more for manufacturers so that they know what to expect from the CPU.

Secondly, I originally confounded two separate temperature markers: Tjmax and TCC activation temperature, and treated them both as Tjmax. The real situation is:

Tjmax (T junction max): The temperature, measured at the CPU core(s), at which a THERMTRIP# signal is sent, telling the CPU to immediately shut down. This is the temperature at which the CPU will incur immediate damage if it ever crosses. Intel does not provide specs for Tjmax, but they do give a ballpark figure of 130C for their processors.

TCC activation temperature: The temperature, measured at the CPU core(s), at which a PROCHOT# signal is sent. This is the signal that activates throttling of the CPU. In essence, the CPU will rapidly step down voltage and clock speed until temperature drops below the TCC activation temperature. If this doesn't work, the CPU will cycle the clock on and off repeatedly (effectively only remaining active a fraction of the time) to reduce temperatures.

TCC activation temperatures are published, and seem to be in the region of 90-100C (for typical desktop processors). For example, all 4th-gen (haswell) i7 processors with an 84W TDP have a published TCC activation temperature of 100C. However, Intel also says that actual TCC activation temperatures are calibrated for individual processors and may differ from published values.

So, the bottom line is, the TCC activation temperature is the temperature at which the CPU will begin to throttle itself. This temperature is usually around 90-100C - well above typical operating temperatures unless you have a defective cooling solution. Tjmax is the temperature at which the CPU will perform an immediate shut down to prevent imminent thermal damage. Intel ballparks Tjmax to be around 130C.

 

[basics]

One of the most professional answers i got over the web and i`m not that young. Thank you.