[SOLVED] How could I locate the temperature sensors on some given CPU?

[tom's]

Hello, all. I'm working on a project about cooling/thermal behavior of cpus, and I was curious to see if I could find the physical locations of a CPU's thermal sensors. I was hoping to be able to compare the temperature reported by the sensors to other locations/hotspots on the chip, but I would need to know the locations of the sensors first. I've looked through some intel cpu datasheets and some research papers, but I've had trouble finding info about the actual locations of the sensors. If anyone could provide me with any info for any cpu, or point me in the right direction, that would be a great help, thanks!

 

[drea.drechsler]

The answer depends heavily on the specific CPU. Some of the earlier Intel CPU's with temp output reputedly had a temperature sensing diode on the die. Before that the only sensor was on the motherboard, usually underneath the socket.

Modern CPU's use different methods and, in AMD's case, aren't really 'sensors', per se, but the result of an algorithm that uses a combination of other telemetry data. At least, this is what I've read from the most cogent sources. It's generally not considered an accurate temperature, but mainly just an indication of the thermal state of the CPU at a very narrow slice in time (which is usually in the past considering how fast CPU's work). FX processor temps were often laughably crazy, especially at low processor useage. In Ryzen, it's also highly localized as the sensors used for the telemetry (called SenseMi in early Ryzen marketing) are scattered across the die(s) in hundreds of locations. So trying to narrow it down will be difficult to say the least.

Interesting blurb by Martin, HWInfo64 author:

IMPORTANT - CPU Core Temperature Measuring - Facts & Fictions

Intel CPUs: Later Intel CPUs feature a Digital Thermal Sensor (DTS) which measures the temperature for each core. Since many users are confused about certain values measured, there is a clarification needed. First, the value read from the DTS is not an absolute values in degrees Celsius, but...

www.hwinfo.com

You might consider joining the forum and addressing some questions directly to him. He's very responsive and should either point you to some good info or answer what he can.

 

[Bazzy 505]

It varies from cpu but generally depending on cpu make, they're usually located on interposer, soldered on the socket side of package or integrtated within cpu die itself.
You must bear in mind that most cpus have multiple sensors measuring temperatures in different parts of chip. So there is no one single place applicable.
These sensors are nothing more than a heat sensitive resistors, mostly NTC type ( resistance falling with as temperature goes up) the accuracy of which is typically within 2-3 deg. So these days they're generally accurate enough for intended purpose. Now these termistors are connected to circuit that converts the voltage returned to digital value. Most of those "inaccuracies" is from software solutions not interpreting these raw values correctly 😉

CPUs with faulty probes don't go to retail nowdays, but back in Pentium III / Athlon days it was not considered a major defect. In fact for the longest time AMD didn't even have core temperature probes, all they mesured it was package and socket temperature