CPU Temp weirdly high at start up and on idle, maybe reporting wrong?

[Nexus1357]

Hi all,

Today I was playing a not very graphically intense visual novel style game, when I noticed quite a lot noise coming from my CPU fan, going from that I looked up how to check system temps on linux, as I'm a relatively new user. From there I downloaded Psensor and both that and the sensor command were reporting unusually high temps of 80+ celcius. I then contacted my tech-savvy friend who got me onto linux, we then tried to figure the issue out by:

• Installed Btop and confirmed it still shows the unusual temps on Btop even though it was reporting a cpu usage of about 5% at 86 celcius.
• We ran sensor detect, and accepted all defaults, we then rebooted the pc.
• We attempted cat /sys/class/thermal/thermal_zone*/temp and it told us that no such file existed. Also when we ran ls /sys/class/thermal all we got were cooling devices.
• As a sanity check, we opened up system manager and created a new page specifically for checking the CPU temp, and it again reported high temps 85 - 90 celcius in all of my cores, even though CPU usage was again only 5%.

Here are my system specs:
CPU: AMD Ryzen 5 3600 6-core processor
Motherboard: ASRock B450M-HDV R4.0
OS: Kubuntu 26.04 LTS running Linux 7.0.0-29-generic
GPU: NVIDIA GeForce RTX 2060 Rev. A

[Snowhog]

Desktop or laptop? When was the last time you cleaned the insides; clearing out the dust?

[Nexus1357]

Desktop or laptop? When was the last time you cleaned the insides; clearing out the dust?

Updated my post to include I'm running it on a desktop PC, and a few months ago, however I am very new user, and previous to me installing linux (about 6 days ago), MSI afterburner would report temps of 40-50 celcius upon boot up and while idle so I don't think dust is the issue in this instance.

[skyfishgoo]

if you were using windows software to manage your fan curves and now you relying on the built in defaults of your firmware, that might explain the thermal managment differencess

if you can still do so, i would suggest booting back into windows and writing down your fan curves so that you can duplicate them in the firmware ... that way linux will be using the same curves

[oshunluvr]

Seems like your kernel is not picking up the temps if the files or thermal zones aren't there.

I assume you ran Windows on the PC before and this didn't occur?

I would try installing an older kernel series and seeing if the temps improve. I'm getting 80-83 under heavy load (95+) on my Ryzen 9 5950x but I'm water cooled.

Maybe you need better cooling fans?