I can't figure out how to stop pl1 and pl2 from throttling on my i7-8550U

[fatojanota]

I've been using throttlestop for a while now but could never figure out how to stop pl1 and pl2 throttling. I repasted my cpu and gpu last week and that helped a little with temps (it still is thermal throttling, mostly during the day, because of how hot it is where I live and my cooler isn't one of the bests). But I'm still having trouble with the power limits. Also, 3 days ago I was having red EDP OTHER limits on CORE, GPU and RING even while idle, but I managed tyo fix that somehow.
So, as I've said, my only problems now are the power limits, any help or explanation will be appreciated since I'm not an expert.
I'll attatch my configs and logs

 

[unclewebb]

What laptop model do you have? Not all power limit throttling problems can be easily solved. Some manufacturers program an embedded controller (EC) to force feed low ball power limits to the CPU. Your laptop is ignoring the MSR and MMIO turbo power limits that ThrottleStop has access to.

Intel gave the 8550U a 15W TDP rating.

Intel® Core™ i7-8550U Processor (8M Cache, up to 4.00 GHz) Product Specifications

Intel® Core™ i7-8550U Processor (8M Cache, up to 4.00 GHz) quick reference guide including specifications, features, pricing, compatibility, design documentation, ordering codes, spec codes and more.

ark.intel.com

Your laptop manufacturer programmed the EC to limit the CPU to 15W during any long term test. It might go higher during the short term but long term, your computer is power limit throttling right at 15W. There is no easy solution for this.

Sometimes it gets throttled back to as little as 5W or 6W. It sure looks like a Dell laptop. Dell used some excessive power limit throttling schemes like this so you cannot even run your 15W CPU at the full Intel 15W TDP limit. ThrottleStop has no solution for many sad sack Dell laptops.

Here is how a Lenovo C930 runs with the same 8550U CPU. Full load and full speed up to 38.5W. If it ever gets too hot it will thermal throttle but at least there is none of the ridiculous power limit throttling at only 5W that some manufacturers decided was OK.

 

[fatojanota]

I forgot about the manufacturer, it is Dell yeah (it's an Inspiron 7472). Sad situation but I'm glad I finally understood this and that there's not really much I can do about it anymore (so I can finally rest), thanks for the clear explanation unclewebb!
Another thing, I saw this CPU had a configurable tdp up to 25w, I was able to change the settings and set it to high tdp. Is this going to improve something? Even if it's just a small improvement, I won't mind.

 

[unclewebb]

Inspiron 7472

Surprise, surprise! I can spot a throttling Dell Inspiron from a mile away. The Inspiron line had throttling issues every year going back to the previous Core 2 Duo era. The Dell engineers dreamed up some truly ridiculous and unnecessary throttling schemes. Other manufacturers were never throttling the CPU down to only 5W. I am still surprised that there was never a class action lawsuit about this issue.

high TDP. Is this going to improve something?

You can try changing the configurable TDP value but I do not think this setting is going to make any difference. The EC turbo power limits seem to override everything else. You will still likely see massive power limit throttling.

 

[fatojanota]

You were right, it didn't make any difference. But I'm at peace now that I now that I can't really do anything anymore, I'm happy even with the limits, using throttlestop helped a lot here
Thank you very much for spending your time explaining things here

 

[PHVM_BR]

I've been using throttlestop for a while now but could never figure out how to stop pl1 and pl2 throttling. I repasted my cpu and gpu last week and that helped a little with temps (it still is thermal throttling, mostly during the day, because of how hot it is where I live and my cooler isn't one of the bests). But I'm still having trouble with the power limits. Also, 3 days ago I was having red EDP OTHER limits on CORE, GPU and RING even while idle, but I managed tyo fix that somehow.
So, as I've said, my only problems now are the power limits, any help or explanation will be appreciated since I'm not an expert.
I'll attatch my configs and logs
View attachment 364275View attachment 364276View attachment 364277View attachment 364278View attachment 364279

Interestingly, a few years ago I already made some adjustments for a friend on an Inspiron 7572 identical to yours, but with a 15.6" screen, and I didn't notice this limitation.

His had an i7-8550U and MX150 with 4GB of Vram.
I changed the original thermal paste, adjusted the CPU undervolt and also overclocked/undervolted the GPU.

I didn't notice this limitation and even checking Lock MMIO worked.

Perhaps the power limit of the EC is activated when the temperature limit (98°C) is sustained for some time...

I remember that the laptop after adjustments could sustain something like ~28/30W without touching the temperature limit under CPU-only loads.
With this power and undervolt the i7 could sustain around 3,4/3,5GHz indefinitely.

In a faster test like Cinebench R23 in a single run it was possible increase power limit (~35W) and complete the test with maximum performance (3,7GHz on all cores) under ideal conditions (mild room temperature and using a laptop stand to move air intake away from the table top).

In cross loads, CPU + GPU, it was possible to maintain up to ~15W on the CPU, also without thermal limitation while the GPU remained at its maximum constantly.

In your log do you have a heavy load on the CPU or CPU + GPU?

In any case, I recommend that you adjust the power limits so as not to force the temperature limit for more than a few seconds.

This way I believe that the extremely low power limit imposed will not be activated.

If in your log the load was only on the CPU you have very low thermal headroom and changing the thermal paste could help increase your limits.

 

[unclewebb]

Perhaps the power limit of the EC is activated when the temperature limit (98°C) is sustained for some time...

Intel thermal throttling works great. It allows the CPU to maintain maximum performance while always keeping the CPU on the safe side of 100°C. I think the Dell engineers decided to reinvent the wheel. I have seen other examples where Dell's EC power limit throttling scheme seems to kick in before Intel thermal throttling starts at somewhere around 90°C.

The log file posted in this thread seems to show the CPU alternating between thermal throttling (TEMP) and PL1 or PL2 power limit throttling which is being controlled by the EC. At one point there is up to 100 seconds of continuous thermal throttling. When the Dell algorithm decides that this is not working, it switches to EC power limit throttling to regain control. The amount of time of each type of throttling seems to randomly vary back and forth.

I agree that avoiding any high temperatures for any length of time should help keep the EC from using its limp power mode throttling scheme.

you have very low thermal headroom and changing the thermal paste could help increase your limits

Totally agree. The heatsinks that many manufacturers used on the low power U series CPUs are truly pathetic. Some Honeywell PTM 7950 might help but there is only so much you can do when a heatsink is under designed. Here is an example from a Lenovo C930. It looks like a piece of Swiss cheese. Maybe the holes were drilled to make it look like a brake rotor off of a high performance car. The microscopic copper paint colored layer does not do much for cooling performance. The three point mounting system will not win any design awards either.

 

[PHVM_BR]

I have seen other examples where Dell's EC power limit throttling scheme seems to kick in before Intel thermal throttling starts at somewhere around 90°C.

Exactly!

On my Precision 7540 I can set the power limits freely, but if the CPU temperature remains at 92°C or more for some time (~2 minutes) the EC power limit comes into play (75W).

I don't know what temperature triggers this limitation on this Inspiron 7472, but it could be the same 92°C or more for a few seconds.

These specific adjustments are unpredictable on Dell notebooks.

In my personal experience, some do not have this limit imposed by the EC.

Even the replacement for the Inspiron 7572, 7580, is a model that has also passed through my hands and which, when well adjusted, becomes excellent.

CPU (i5-8265U/i7-8565U) and GPU (MX150) can extract their maximum simultaneously for extended periods.

Another example of an Inspiron where the power limit imposed by EC does not occur is the Inspiron 5510 with Tiger Lake H35 and MX450. Very good too!

 

[fatojanota]

In your log do you have a heavy load on the CPU or CPU + GPU?

In any case, I recommend that you adjust the power limits so as not to force the temperature limit for more than a few seconds.

This way I believe that the extremely low power limit imposed will not be activated.

If in your log the load was only on the CPU you have very low thermal headroom and changing the thermal paste could help increase your limits.

Hey, thanks for the answer!
I'm gonna follow both yours and unclewebb's advices, do a few testings and post the results later