Troubleshooting: CPU Core temperature readout triple the heat of the other cores

[lijeu]

Hello,
I just put together a machine with an i7--8700K CPU @ 3.70GHz into an ASRock Z370 Extreme4, and I'm worried about one of the temperature readouts -- what do you think this is caused by?

Uploaded image: https://ibb.co/kVv6qp

 

[anotherdrew]

That looks like a faulty sensor. Also, that is a sensor on your motherboard and not one on your CPU. The fact that it does not fluctuate is another indication of a fault.

https://www.hwinfo.com/forum/Thread-Extreme-Temps-Read-on-Nuvoton-NCT6791D

 

[lijeu]

That looks like a faulty sensor. Also, that is a sensor on your motherboard and not one on your CPU. The fact that it does not fluctuate is another indication of a fault.

https://www.hwinfo.com/forum/Thread-Extreme-Temps-Read-on-Nuvoton-NCT6791D

The temperature is fluctuating, and now looks around 108'C -- a friend asked me to install an Intel processor diagnostic tool to see if there's any other info.

Any other thoughts? How do I make sure that this is just a false read? Is it possible to use a laser thermometer to see if there's any part that's actually 60 degrees hotter than the other, lol?

 

[anotherdrew]

You can use a laser thermometer. I would start with the heat sinks (if they put a heat sink on something, they are trying to dissipate heat ... well, ok, some are there to look cool) Next hotspot is going to be your VRMs (small black boxes with a silver square on top that form an L shape around the CPU). The rest of the motherboard should be pretty cool.

 

[lijeu]

I will try doing that. I'm a little worried because upon starting up after being asleep for hours, it looks like the CPU Core is above all of the temperature readouts from 1-3, and 5-6 (somewhere between the low values and the top #4 value).

+- CPU Core : 35.5 30 66 (/lpc/nct6791d/temperature/0)
| | +- Temperature #1 : 33 28 41 (/lpc/nct6791d/temperature/1)
| | +- Temperature #2 : 34 30 43 (/lpc/nct6791d/temperature/2)
| | +- Temperature #3 : 26 26 26 (/lpc/nct6791d/temperature/3)
| | +- Temperature #4 : 103 96 106 (/lpc/nct6791d/temperature/4)
| | +- Temperature #5 : 28 27 28 (/lpc/nct6791d/temperature/5)
| | +- Temperature #6 : 22 22 22 (/lpc/nct6791d/temperature/6)

 

[CompuTronix]

lijeu,

On behalf of Tom's Moderator Team, welcome aboard!

Although you can use your IR thermometer to measure the temperatures of the VRM's, contrary to anotherdrew's suggestion it's pointless to attempt an external IR temperature measurement of the processor. Here's why:

Sensing thermal performance by touch is like feeling a campfire from 3 meters. Since hundreds of millions of nanometer scale transistors are densely packaged into a tiny Die, heat dissipates over relatively large areas and thermal gradients to the cooler, about 3 millimeters from the Cores. (3 millimeters = 3,000,000 nanometers).
Although some heat dissipates to the substrate, socket and motherboard, most heat dissipates to the cooler through several thermal gradients; Cores > Die > internal TIM (or solder) > IHS > external TIM > cooler. Even at 100% workload nothing will feel hot; exhaust airflow, cooling fins, heat pipes, radiator or water block will feel warm, and liquid cooling tubes will have a minimal temperature differential.

To verify the Core temperatures you're seeing in HWMonitor, please download and run HWiNFO - https://www.hwinfo.com/download.php

HWiNFO is known to be a very accurate and reliable monitoring utility. Select "Sensors Only" when you start HWiNFO, then compare "Core" temperatures with HWMonitor. If they agree, then as anotherdrew mentioned, your 8700K has a bad Digital Thermal Sensor for that particular Core. In such an instance I recommend that you RMA that processor, as you can expect to have problems with irregular operation due to false thermal throttling.

Also, Tom's has a Guide you should read: Intel Temperature Guide - http://www.tomshardware.com/forum/id-1800828/intel-temperature-guide.html

Once again, welcome aboard!

CT

 

[lijeu]

Downloaded HWiNFO, and my output of readouts for CPU: Intel Core i7-8700K: DTS looks like:

Core #0 [°C] Core #1 [°C] Core #2 [°C] Core #3 [°C] Core #4 [°C] Core #5 [°C]
0 1 2 3 4 5
33 34 33 34 32 33
33 34 33 34 32 32
33 34 32 35 32 32
34 34 32 35 32 32
33 34 32 34 32 32
33 34 32 33 32 32
33 34 33 34 32 33
33 34 34 34 32 33
37 35 34 35 33 34
35 34 32 34 32 32
43 47 38 37 34 35
34 34 34 34 34 36
39 38 38 40 45 44
42 36 37 37 37 37

So as you suggest, it sounds like I should return this CPU?

 

[anotherdrew]

Going back to your original post with the linked image. I understand you think those temperature readings are from your CPU, but I don't think they are. Why?

1. They are being reported under the motherboard, not the CPU. Normally CPU core temperatures are listed under the CPU and motherboard sensors are listed under the motherboard. Like this:
https://linustechtips.com/main/topic/889452-overclocking-my-i7-8700k/

2. HWmonitor for that motherboard's I/O chip lists 6 temperatures, even if you have a 4 core CPU. Like this:
https://github.com/openhardwaremonitor/openhardwaremonitor/issues/725

3. If part of your CPU (or motherboard) really was running at 108C (even with a +/- of 5C) things would be going wrong.

4. And finally, using different software (HWinfo, rather than HWmonitor) you get completely different results.

It seems logical to me that that very high temperature you saw is the result of a faulty motherboard sensor (not one on your CPU) as I stated originally.

 

[CompuTronix]

Downloaded HWiNFO, and my output of readouts for CPU: Intel Core i7-8700K: DTS looks like:

Core #0 [°C] Core #1 [°C] Core #2 [°C] Core #3 [°C] Core #4 [°C] Core #5 [°C]
0 1 2 3 4 5
33 34 33 34 32 33
33 34 33 34 32 32
33 34 32 35 32 32
34 34 32 35 32 32
33 34 32 34 32 32
33 34 32 33 32 32
33 34 33 34 32 33
33 34 34 34 32 33
37 35 34 35 33 34
35 34 32 34 32 32
43 47 38 37 34 35
34 34 34 34 34 36
39 38 38 40 45 44
42 36 37 37 37 37

So as you suggest, it sounds like I should return this CPU?

A screenshot would be more revealing. Regardless, the Core temperature numbers from HWiNFO do not suggest anything concerning or unusual with your processor's thermal sensors.

Intel's specification for DTS accuracy is +/- 5°C. This means when all Cores are at a steady 100% workload, the difference between highest and lowest Core temperatures should not exceed 10°C. It's typically quite rare for Intel's Digital Thermal Sensors (Core temperature sensors) to malfunction where any single Core exceeds 100°C, while all other Cores are basically at idle temperatures.

HWMonitor is known to sometimes be inaccurate, and to mis-assign and mis-label sensors, Depending on motherboard manufacturer, model and your board's Super I/O (Input/Output) chip, HWMonitor might also show an absurdly high temperature where no sensor is present.

I suspect this problem is yet another instance of HWMonitor showing erroneous information. For an additional cross-check of your Core temperatures, please download and run Core Temp - http://www.alcpu.com/CoreTemp

Core Temp is a quick and simple utility that gives the most critical information you need to know, which is of course, your Core temperatures. Core Temp is also known to be accurate and reliable.

If Core Temp and HWiNFO agree, then there's nothing wrong with your 8700K, in which case, I would recommend that you forget about using HWMonitor.

CT

 

[lijeu]

So I ordered a new CPU and installed it, and it looks like it isn't my CPU after all, as you can see my readouts from the installation:

https://ibb.co/coyA7p

I guess this means this is my motherboard?

 

[anotherdrew]

As both CT and I said, there does not seem to be anything wrong. The 106 reading is probably from a faulty (or possibly non-existent) sensor. Either way, it's a sensor on your motherboard, not on your CPU. Stop worrying about this.