where is Tcase sensor really located?

[ckooii]

Hey guys, so it is said that the Tcase sensor is located inside the IHS and measures its temps, but IHS is a piece of copper thats separated from a processor so how the hell does it transfer temperature data to it? And where the hell really is that sensor? U can just take IHS off and there are no contacts with cpu whatsoever so how can the temps be read?

also, if u lap the processor can u reach that sensor?

 

[Sedivy]

No it's likely located on the motherboard, as close to IHS as possible, and approximates the true temperature. Like the pic shows:
https://forums.anandtech.com/threads/can-you-damage-a-sandy-bridge-by-overclocking.2250147/page-2

 

[CompuTronix]

ckooii,

There is no Tcase sensor on retail processors; Tcase only exists on Engineering Samples in Intel's labs, so the end user can not measure Tcase.

Near the top of the CPU's Forum there's a Sticky you should read: Intel Temperature Guide - http://www.tomshardware.com/forum/id-1800828/intel-temperature-guide.html

Section 1 - Introduction

" ... Core temperatures are measured at the heat sources near the transistor "Junctions" inside each of the Cores. CPU temperature is instead a single external measurement centered on the surface of the CPU's "Case" or "Integrated Heat Spreader" where the cooler is seated.

CPU temperature is a factory only measurement used for Intel's "Tcase" Thermal Specification, so Tcase is not Core temperature. When users look up their processor's Thermal Specification at Intel's Product Specifications website, they often don't realize what Tcase actually means. Since there are many software utilities for monitoring Core temperature, users unknowingly assume Tcase must be Core temperature.

Core temperature (Tjunction) is considerably higher than CPU temperature (Tcase) due to differences in the proximity of sensors to heat sources ... "

Section 3 - CPU Temperature

"Also called "Tcase", this is the temperature shown in Intel's Thermal Specification (does not apply to 7th Generation). Tcase is a factory only measurement on the surface of the Integrated Heat Spreader (IHS). For lab testing only, a groove is cut into the surface of the IHS where a "thermocouple" is embedded at the center, which measures the temperature of the entire CPU. The stock cooler is then seated and the processor is tested under carefully controlled conditions at a steady 100% workload.

One of two different methods are used to display “CPU” temperature in BIOS and in monitoring utilities.

Previous Method: Processors for Core 2 Socket 775 and Core i Socket 1366 use a single Analog Thermal Diode centered under the Cores to substitute for a laboratory thermocouple. The Analog value is converted to Digital (A to D) by the motherboard's Super I/O (Input / Output) chip, then is calibrated to look-up tables coded into BIOS. For these processors, the monitoring utility provided by your motherboard manufacturer on the Driver DVD displays “CPU” temperature in Windows. Accuracy can vary greatly with BIOS updates, so "CPU" temperature can be grossly inaccurate.

Present Method: Processors for Core i Sockets 115x and Core X Socket 2011 no longer use an Analog Thermal Diode, but instead substitute the "hottest Core" for "CPU" temperature, which is a contradiction in terms. This is the temperature shown in BIOS, and on some recent motherboards is displayed on the two digit "debug" display. For these processors, the monitoring utility provided by your motherboard manufacturer on the Driver DVD displays “CPU” temperature in Windows, but is actually the "hottest Core", which is also called "Package" temperature."

CT

 

[ckooii]

please let me be sure if i got it right

"Tcase is a factory only measurement on the surface of the Integrated Heat Spreader (IHS)."

so they put a thermocouple in the IHS at their lab, get the cpu to 100% load with their xxxxxx stock cooler, see it throttle at lets say 71 degrees on IHS sensor, and make it a 'critical case temp' aka Tcase? Cus i dont really see other reasons for calling it critical temp on their website besides that it throttles in their lab.

And then they remove the sensor and ship the cpu to us? So that Tcase is kinda useless to us that may be a reason why they removed it in the 7th gen cpu specs on their site.

Really appreciate ur article btw, cool stuff

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[CompuTronix]

ckooii,

Keep in mind that Tcase is not Core temperature, which is considerably higher. Tj Max (Tjuntion Max) is Throttle temperature, which is Core temperature. Most desktop processors Throttle at 100°C.

Tj Max has always been the limiting Thermal Specification; not Tcase.

Only Engineering Samples have a groove cut into the surface of the IHS for a Tcase "thermocouple" sensor. Intel does not install, test, then remove a Tcase sensor from retail samples and ship them out to buyers.

In the Guide, Section 7 - Power and Temperature, explains in detail why Tcase and Tj Max are inconsistent with maximum recommended Core temperature, which is 85°C.

But yes, you're right; Tcase is a useless spec except to developers of cooling solutions. To the end user like you and me, Tcase is a confusing and misleading specification that should have been changed to Tjunction (Tj Max) years ago, just as they finally did for the release of 7th Gen Kaby Lake this past January.

CT