Possibly incorrect PCIe x1 sensor readings

Hello! I have a MSI PRO B650-S WIFI motherboard (MS-7E26), which has a NUVOTON NCT6687D-R chip. Ubuntu 24.04 LTS 6.8.0-39-generic.

Installed:

PCIe 4.0 x16 video card (cpu line).
NVME drive M2 PCIe 4.0 x4 (cpu line).
Wireless module is pre-installed in the M.2 (Key-E) slot. The remaining slots are not used.

Before installing this project, I did not have access to many sensors: fan, voltage, socket temperature, vrm, etc. All major sensors are now available. But I found strange readings on PCIe x1. The temperature constantly fluctuates between 81 and 84.5°C. It has never been lower or higher, the room temperature is from 24 to 31°C. At the same time, a stress test of the CPU or GPU, increasing the fan speed to 1800 rpm (6 air intake, 4 air exhaust, closed case) does not affect the temperature.

CPU:            +56.0°C  (low  = +53.0°C, high = +59.0°C)
System:         +42.0°C  (low  = +41.0°C, high = +42.0°C)
VRM MOS:        +47.5°C  (low  = +44.0°C, high = +47.5°C)
PCH:            +45.0°C  (low  = +44.5°C, high = +45.5°C)
CPU Socket:     +45.0°C  (low  = +43.0°C, high = +45.0°C)
PCIe x1:        +82.0°C  (low  = +81.0°C, high = +84.5°C)
M2_1:            +0.0°C  (low  =  +0.0°C, high =  +0.0°C)

Measurement with a pyrometer, and then with a thermal imager, did not show points with a temperature above 39°C when idle; during stress tests of the components - 45°C, vrm - 58°C. All fans were turned off and the PC case was closed. In Windows, I could not find at least one sensor with similar readings.

Tell me, is this an incorrect sensor measurement by this module or do I still have a problem with the motherboard at the component level?

1024 1025

Fred78290 / nct6687d

Possibly incorrect PCIe x1 sensor readings #98