Legion Pro 7i, i9-13900HX. PL2 limit reason in log file

[daigororo37]

When running CB R23, I'm getting PL2 limits in the log file and I can see CPU is throttling (unless I am reading this log file incorrectly). Are there any settings I have set incorrectly? I am new to undervolting, any pointers would be appreciated. Thanks!

Log file:

Throttlestop 9.6 Settings

Note: P Cache undervolt value same as Core. E Cache -50 mV (I might reset this back to 0 actually).

 

[unclewebb]

I can see CPU is throttling

You are seeing this correctly. The FID column in the log file is down to 38.xx instead of 50+. 3800 MHz compared to 5000+ MHz is throttling.

PL2 power limit throttling is the cause and this is happening right at 190 Watts. In the TPL window in the Power Limit Controls section you can clear the Disable Controls check box and you can increase the Short Power PL2 limit higher than 190W. This can be used to get beyond the 190W limit but instead of power limit throttling, you will end up with thermal throttling. Inadequate cooling is costing you about 1200 MHz during Cinebench testing.

It looks like your 13900HX is just a hot running CPU or your room temperature is very hot. The Legion Pro comes with excellent cooling. 190W is just too much heat to dissipate, even for a well designed laptop.

I might reset this back to 0 actually

That would be a mistake. Less voltage is less heat. More voltage is more heat.

If your -140 mV undervolt is not stable, try setting the mV Boost feature to 150 or so. That can improve stability which can allow you to run a large undervolt reliably. There are no other options when you are hitting 190W.

 

[daigororo37]

Inadequate cooling

Thank you so much for your explanations. I now have this laptop sitting on a cooling fan. Just to test things further and understand what is going on, I increased the PL1 and PL2 limits in TPL section to 190 and 210, respectively, as you have suggested; just wanted to see what would happen really. Re-rerunning CB23, PL2 has disappeared from the logs but now seeing VRTDC (which I imagine is not a good thing haha). What I don't fully understand (and probably stems from my lack of knowledge on CPU's) is that the max temp was 87 *C during this run, so there's still some room here isn't there? Also, why is the CPU throttling so fast going from lines 10669 to 10671 when there are no limit reasons against these time points. I know the temp has increased by 20 *C drastically as well as the power; I guess this is just the way it's supposed to behave fundamentally?

 

[unclewebb]

VRTDC

You are throttling because you have reached the voltage regulator current limit. In other words, you have hit the wall. Not many laptops are designed and capable of providing 190W to the CPU. PL2 power limit throttling at 190W might be necessary to keep your voltage regulators from catching on fire. Either way, throttling is throttling. The CPU is slowing down a similar amount in both log files you posted.

Try calling Lenovo to complain. Tell them you need improved cooling and some power hungry voltage regulators from a high end desktop motherboard.

why is the CPU throttling so fast going from lines 10669 to 10671

I think it is pretty obvious. Your laptop is not built to deliver more than 190W. Significant throttling is the result.

I increased the PL1 and PL2 limits in TPL section to 190 and 210, respectively, as you have suggested

Did I say that? Do not follow the advice of anyone you meet on the internet. Pushing an Intel mobile CPU to 190W will probably not hurt it but trying to get your voltage regulators to deliver 190W might hurt them. What the voltage regulators are capable of can change as they heat up, which they will.

 

[daigororo37]

Did I say that?

My apologies!! I misinterpreted what you wrote. Thank you for all the helpful info!