[Solved] M720q throttles only in Linux

[mietzen]

Hi,

I bought an M720q with a Pentium Gold and upgraded it with a Core i7 8700 (65W). Everything runs smoothly under Windows the CPU briefly pulls up to 45W and then settles down to 35-37W, with temperatures averaging at 75°C / peaking at 80°C under full load. This is exactly what I expected.

However, I don't want to run Windows on it. I want to run Proxmox.
When I boot into Linux, the CPU is immediately throttled to 20W, then further down to 15W, and eventually as low as 7-8W, running only at 800MHz. This happens within 5 minutes under load (s-tui). The temperatures range from 35-45°C, so that doesn't seem to be the issue.

Here's what I've tried:

Hardware:

• Board diagnostic (Full): No errors detected
• CPU reseat
• Checked CPU thermal paste and repaste
• Tested the CPU (8700) in another machine with Linux, works flawlessly
• Single-channel RAM
• Only NVME Drive
• Only SATA Drive
• No drives, boot into Linux live disk
• BIOS update (M1UKT74A/1.0.0.11 as of November 28, 2023)
• BIOS reset

Software:

• efi setup_var (0x7BD on/off)
• Linux DMESG / Journalctl --system show no errors or information regarding cpu throttling
• Linux PL1/PL2 in intel-undervolt has no effect
• Linux power target: Performance has no effect
• Tested various distros: Ubuntu 22.04, Debian 12, Proxmox 8, Fedora 39

I've also ordered a 90W power supply, but I don't think that's the issue.

Did I overlook anything?
The Pentium Gold doesn't have any issues running Linux, it doesn't throttle and stays at 3,1Ghz.

For me it seems like this particular CPU is just slightly incompatible with this particular board and/or the Linux Kernel is picky.

If anyone has access to old M720q Bios versions, please let me know, this is something I haven't tested.
Edit: Found old versions on the chinese site: 联想_ThinkPad|ThinkCentre|ThinkStation服务与驱动下载_联想BIOS 升级程序(Windows 11/Windows 10 64-bit)

I'll upload all of them to archive.org, done: Lenovo M720q Bios : Lenovo : Free Download, Borrow, and Streaming : Internet Archive

Cheers Nils

 

[Tech Junky]

What's the issue other than running more efficiently than Windows? That's kind of the point of using *nix instead for things you want to be stable and efficient. I think the lowest I've seen this go though is 0.8ghz depending on what's running at the moment.

I had this setup running on a 8700K / 12700K and now the AMD.

 

[mietzen]

The CPU throttles to 7 Watt / 800MHz under load without any reason, that might be efficient but also very very slow.

 

[gregsachs]

Did you see this? Possibly related..
https://www.reddit.com/r/thinkpad/comments/etiotf

 

[mietzen]

Did you see this? Possibly related..
https://www.reddit.com/r/thinkpad/comments/etiotf

Thanks I already tested GitHub - erpalma/throttled: Workaround for Intel throttling issues in Linux., next I'll try older BIOS versions.

 

[mietzen]

Did you see this? Possibly related..
https://www.reddit.com/r/thinkpad/comments/etiotf

Thanks, that was it! With some caveats... I wrote it all together in a Gist:

m720q Setup: i7 8700 65W

m720q Setup: i7 8700 65W. GitHub Gist: instantly share code, notes, and snippets.

gist.github.com

To summarize:

1. Deactivate secure boot
2. Be sure that secure boot is real off!
3. Set the power limit to exactly 35W one even one Watt more!

I also got the feeling that the new power supply may fix the issue as well, I'll will update this post as soon as it arrives.

 

[mietzen]

Yes, it was the power supply. With the 90W power supply, I can operate the CPU at over 35W. The aluminum cooler handles it quite well up to 55 watts, then all cores reach about 90°C, and the fan becomes quite audible, but far from full speed. However, my idle power consumption with the 90 Watt power supply has also increased from 4-5 watts to 10-11 watts (with the same settings PL1: 35W, PL2: 35W). I'll have to reconsider what is more important to me

Edit: I measured wrong! The idle consumption is unchanged!