Do I trust CPU Temp Sensor or Motherboard CPU Temp?

[Christopher Aubert]

HWMonitor always gives me two different readings, the CPU sensor is always incredibly erratic and all over the place (readings will spike from 37-45 in an instant, then back again), and it's readings are always higher than the motherboard's (playing Overwatch the CPU's sensor reported a max of 80(!) while the motherboard's sensor reported a max of 72).
Here's a little visualization of my system and airflow: https://gyazo.com/f8bf513dd82589aeebb2750872a73225
I generally follow the motherboard reading, just because it sounds more believable and doesn't randomly spike.

(Also if you're at it can you explain the temps being so high? Under load the highest I've seen is 72, which with this CPU cooler, is a little high, especially with this being a stock i7.)
PC: https://pcpartpicker.com/list/nG4XYT

 

[jay32267]

CPU temperatures can be very erratic and 80 is not that high.
I'm really not seeing anything I would be concerned about.
If it's running good I might leave it alone.

 

[CompuTronix]

Christopher Aubert,

To answer your question in the title, "Do I trust CPU Temp Sensor or Motherboard CPU Temp?", the answer is neither; you trust "Core" temperature.

Like many 3rd party freeware monitoring utilities, HWMonitor often does not correctly identify and assign the appropriate label to every sensor for every motherboard model from every manufacturer. In HWMonitor under "Intel Core i7 8700", then under "Temperatures", you should see "Core #0" thru "Core #5", which are the Core temperatures for each of the six individual Cores.

Core temperatures are typically the most critical temperatures to monitor ... more so than any other computer temperatures. Core temperature is where your focus should be.

Here's the nominal operating range for Core temperature:

Core temperatures above 85°C are not recommended.

Core temperatures below 80°C are ideal.

Tom's has a Guide for this: Intel Temperature Guide - http://www.tomshardware.com/forum/id-1800828/intel-temperature-guide.html

It's a Sticky near the top of the CPU's Forum. Give it a read. See Section 4 Paragraph 3, and Section 13 Note 1 for explanations concerning the temperature fluctuations you're seeing in HWMonitor.

At 100% workload, it is normal and expected for Core temperatures to be higher than any other temperatures, and it is also normal and expected for Core temperatures to fluctuate widely and rapidly under lower workloads, especially at idle. Moreover, "CPU" temperature may correspond to "Package" temperature, which is the hottest "Core".

The most accurate and detailed monitoring utility is HWiNFO - https://www.hwinfo.com/download.php

Download HWiNFO "Portable" and run "Sensors Only" to cross-check the information you see in HWMonitor for accuracy. Don't be surprised if the values and labels in HWiNFO do not agree with those in HWMonitor. Between the two utilities, I would always trust HWiNFO first.

For a simple and very straight forward monitoring utility, "Core Temp" is highly recommended - https://www.alcpu.com/CoreTemp/

Core Temp will give you the most critical temperature information, which of course is "Core" temperature.

Remember to factor in ambient (room) temperature. Core temperatures increase and decrease with ambient temperature. Standard or normal is 22°C or 72°F.

Additionally, there is no "Motherboard" sensor for Intel Core i 2nd thru 8th Generation processors with respect to temperature. "Motherboard" temperature may instead actually be a sensor for Voltage Regulator (VRM) temperature, which for a stock 8700, should be lower than any "Core" temperatures.

CT

 

[madmatt30]

It's a coffee lake i7, erratic temp spikes are normal because
1. They run hot
2. The die Tim is subpar
3. Multicore boosts go way out of the chips advertised specs

While that little noctua may have been great for previous gen i7's I'd argue that for your current cpu it's just barely acceptable.