CPU keeps getting throttled to oblivion (~400 MHz)

I have a strange problem, where my CPU gets throttled whenever the utilisation goes a bit high. There’s absolutely no way to get sustained high use. And the throttled speed goes down to as low as 400MHz!

I’m on a ThinkPad T495s

$ inxi -Cm
Memory:    RAM: total: 13.33 GiB used: 6.49 GiB (48.7%)
           Array-1: capacity: 64 GiB slots: 2 EC: None
           Device-1: DIMM 0 size: 8 GiB speed: 2400 MT/s
           Device-2: DIMM 0 size: 8 GiB speed: 2400 MT/s
CPU:       Info: Quad Core model: AMD Ryzen 7 PRO 3700U w/ Radeon Vega Mobile Gfx bits: 64 type: MT MCP cache: L2: 2 MiB
           Speed: 435 MHz min/max: 1400/2300 MHz Core speeds (MHz): 1: 435 2: 436 3: 870 4: 871 5: 435 6: 434 7: 871 8: 871

I looked at the scaling_governor, it’s set to schedutil, which according to the kernel docs is the right thing to do. When I manually set all the governors to performance, I still don’t get any significant improvement (as you can see from the inxi output).

Can someone shed some light here?

Maybe it is a cooling problem? Does it throttle when the CPU temperature hits a certain value?

It does become a bit hot, but not much. As per conky it never even touches 60, hovers around low 50s.

I have opened up the laptop too, there wasn’t much to be cleaned apart from what you would expect for a year old laptop.

I also looked at the BIOS, I think the options were battery optimised, balanced, and performance. If I remember correctly balanced was selected there. And since I’m mostly plugged in, I would expect balanced and performance to be the same.

In the past (on other ThinkPads I have owned), I have run long multi hour long computations, with CPU temps touching 70-80 at times. Which is why I find this so perplexing, and not really sure how to debug.

Is the throttling when on battery, AC, or both?

I had a bizarre issue with the CPU throttling to below the minimum frequency but only when on battery. The solution was to clean the battery contacts. Laptop CPU dropping to unusably slow frequency on battery

But mine has a removable battery while the T495s does not seem to. Still maybe something to consider.

I’m rarely on battery. This happens when I’m plugged in. Usually triggered by Zoom/Teams eating CPU (most typical scenario), or say, if I try to transcode a video.

When did the issue start? Doesn’t sound normal. Might want to monitor what’s going on with sensors.

Can’t be sure, I can only recall these issues starting to annoy me around Nov-Dec. Good idea with sensors, I’ll setup a cron job to log everything.