[RESPONDED] Temperature skyrockets to 100C with only 2 cores at 100% load (Linux, AMD 7640u)

Community Support
1

I regularly execute really CPU intensive code on my AMD 7640u Framework 13. I usually monitor some system analytics and I noticed when only 1 or 2 cores being hit (100% load) the CPU temperature reaches and maintains 100C. The other cores are basically idling. The CPU fan goes crazy when this happens.

Is this expected behavior? I’ve never had this happen on any other laptop I’ve owned. This is behavior I would certainly expect if the entire CPU was being hit with 100% load on all cores, however this isn’t something I would expect with only 1 or 2 cores being hit.

I’m running the latest version of Fedora.

The process using the cores is a Wolfram Mathematica process.
Specifically, I’m executing a differential equation solver. The specific part that is using a single (or 2) core is when the solver seeds the initial guess. It computes a guess for the solution over the computational grid (which for some reason isnt parallelized).

If I use the program stress-ng with command

 stress-ng --cpu 2 --timeout 2m --metrics

then the temperature asymptotes to 90C with no other process executing

Is this expected behavior? It seems like the temperature is too high for such a load. Would it be worth it to redo the thermal paste on the heat sink?

2

Did you identify the processes using up these 2 CPU cores?
That would help.

1 Like
3

Yea, its Mathematica. I updated my post

4

Presuming you’re reading the temperature from acpi --verbose value Thermal 1, the highest I could get mine – even running stress-ng with --cpu 12 – was 97C. At that point, the fan kicked in and drove the temperature down to under 94C, sustained (and even then, the fan was not running full tilt the whole time – for the stretches where the fan did run full tilt, it could drive the temperature back down to 90C). If I hit only two cores, temperature climbs super slow, and doesn’t seem to break about 85C. My ambient is 20.2C, and my board has full topside access to cold air (no chassis), with the heatpipe above the CPU (i.e., the board is mounted sideways), so my cooling is about as unfairly good as it gets. Are you in a particularly hot room? Is the airflow around your intake/outlet obstructed at all? The fins are all straight on the radiator and letting the fan air pass through fine?

5

This does sound a bit warm to me, before re- pasting, I would want to test this with another kernel. See if there similar behavior there. What kernel are you using and how up to date is your installation?