PC Processors

[SimonHF]

Hello! I'm running Ubuntu 22.04 Linux on a RYZEN 9 3950X and switched on frequency monitoring and noticed that the last 8 vCPUs seem to be pinned at 3.5 Ghz even when the system is idling. Is this to be expected and why?

[misterj]

SimonHF, this is not expected. I know little about Linux and the screenshot you posted. Is there any way you can install W10/W11 and run some tests for me? If so, let me know and I will tell you what I would like you to do. Here is the link to AMD Support. I suggest you open on a ticket. Thanks and Enjoy, John.

[SimonHF]

Thanks for the quick reply and clarification, John. Yes, I can dual boot into W11. And I'm happy to run the tests you will suggest... Would you prefer to keep the dialog here for now, or switch to the AMD Support ticket? Thanks in advance!

[misterj]

SimonHF, this is a user support forum. I do not work for AMD and my opinions are my own. You can open a support request at any time and I suggest you do where I pointed to above. If you can run W11 on the HW not a VM, then install Ryzen Master (RM) from here, make sure all AMD drivers are from here. Please post screenshots of RM both Basic and Advanced views running Cinebench R23, only images of RM. We'll go from there. It has been some time since I ran a VM but on the surface I'll ask, why do you think all processors at 100% drops the cores to 1100 MHz is expected? Unless you are exceeding some temperature, current or power limits all cores should continue at full speed. Thanks and enjoy, John.

[SimonHF]

Thanks for the instructions! I'll have a got at getting the results for you!

In the meantime, why did I expected the CPU frequencies to drop at full usage? Er, because I'm running the CPU in a laptop [1] and I'm guessing due to power and or cooling limitations, it doesn't take any chances

However, I noticed at idle the CPU temperature is about 58 degrees, and at full CPU usage about 75 degrees. I understand that the CPUs can go up to close to 100 degrees, so maybe the throttling is due to power limitations? This particular laptop has a 330W AC adapter. Not sure if that could be the reason for the Mhz throttling?

I've never tried to tweak settings, and I don't know which settings to tweak or how, to affect Mhz throttling in relation to temperature and or power usage. Maybe you kindly have some pointers for me? I'm assuming maybe something in the BIOS or something like that?

Thanks for your help so far!

[1] https://eurocom.com/ec/configure(2,481,0)NightskyARX315

[misterj]

Thanks much, SimonHF. Your processor's max temperature is 95C found here with more specifications. Ryzen Master (RM) is used for OCing, etc. I recommend to users to stay out of BIOS but I guess you have no choice. I do little in BIOS and suggest you see if there is a site that does this. Since you are running a LT RM may not install. I have a 1250 Watt PSU on my DT (3970X) and suspect your 330W may be insufficient and you may get some crashes according to how the system vendor has set some throttling limits. If you really want to go fast, you'll need a DT with good cooling, PSU, and MB. Please give it a try and we'll see how it goes. Thanks and enjoy, John.

[SimonHF]

Finally got around to running Cinebench R23 like you wanted, and here are the resulting screen shots:

Screen shots while idling:

Screen shots while rendering:

So during rendering RM appears to show the just over 2,000 Mhz on each core.

I also include a screenshot from Task Manager which seems to show different results for the last 8 cores for some reason. Any ideas why that happens? And is it related to Linux htop showing different Mhz during idling for the last 8 cores?

Here are the final results of the Cinebench R23 run:

Looking forward to your comments.

[SimonHF]

Update: I also notice that if I generate a load so that each vCPU is 100% busy, the MHz for each vCPUs goes down to about 1,100-ish Mhz for all vCPUs, as expected. So the Mhz-behaviour when non-idling seems reasonable. If that helps...

[SimonHF]

Hmmm... so the above comment about 1,100 Mhz (via htop) with all 32 vCPUs busy was on Linux Ubuntu. However, I just posted the screen shots above for 32 vCPUs busy on Windows 11 via Cinebench R23 which shows about 2,000 Mhz (via Ryzen Master and hwinfo) when all 32 vCPUs are busy.

Question 1: Is htop just somehow getting the Mhz reading wrong somehow? Or...

Question 2: Why is the Mhz almost two times bigger on Windows 11 than on Ubuntu 22.04?

[SimonHF]

This bug [1] seems to have exactly the same symptoms as my issue. Only the first 24 out of 32 CPUs have a 'cpufreq' folder. The link [2] suggests that the BIOS is at fault? Anybody have any experience with fixing this kind of issue? Thanks!

[1] https://answers.launchpad.net/ubuntu/+question/694068
[2] https://bugzilla.redhat.com/show_bug.cgi?id=1874538#c2