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39 Posts

05-31-2021

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  • Posts: 39
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P14s gen 2: thoughts and observations on throttling

2021-06-14, 19:36 PM

As these forums show, erratic CPU throttling is a widespread problem among the Lenovo lineup. Google searches suggest that Windows 10 with recent gen Intel chips may be prone to throttling issues. Other manufacturers (e.g. HP, Dell) also get complaints; but complaints about Lenovo machines are especially common, and it seems Lenovo has more trouble than others finding an ok resolution.

 

I noticed throttling behavior on my machine (P14s gen 2, 1165G7, 16GB RAM, 4k screen, owned now for ~2 weeks) from the start: sudden drops during normal application load, even when the machine is at baseline temperature; bouncing between 100% and 5% performance instead of finding a stable mid-point; throttling during video calls; etc.

 

It's not a gaming machine, and I don't expect it to handle that type of load well. But it should be able to handle things like Capture One, Lightroom, Fusion 360 (and of course video conferencing); it does well enough, except when the machine suddenly becomes unresponsive for a few minutes. For example, yesterday I started up the machine (from room temperature), opened up Fusion 360, and in that moment the CPU was throttled to minimum (5W / ~0.4GHz), unresponsive. Minutes later it bounced back to full performance, and from then on the application ran perfectly.

 

I know people would ask, so: I'm on all the newest BIOS, firmware, drivers etc., according to Vantage, Windows Update, the Lenovo support site, and Google. All diagnostics are green.

 

Findings so far:

  • The system can perform very well (upper end of benchmark range for this architecture) when throttling doesn't hit. When the throttling bug hits, benchmarks are well below the low end of the range. 
  • It's not a hardware defect. Service exchanged my logic board, and it had zero effect on the throttling issues.
  • Thermal design seems to be ok. When the system is running unthrottled at full load for a while, the CPU may hit its thermal cutoff and slow down a little bit, but active cooling overall keeps the system at an ok temperature (well under ~80C).
  • The battery is a thermal weak spot. Once battery temperature readings hit 50C (which usually takes a while), the system starts throttling back aggressively. Additional cooling from outside can help avoid that.
  • In Windows 10, the "best performance" setting (from the battery icon) throttles much more aggressively. "Better performance" gives me, well, better performance than "best performance".
  • Sudden load increases, esp. involving both CPU and GPU, most often result in sudden throttling. E.g. starting up Lightroom. After that first "panic" has worn off, the system runs stable at high load. "Best performance" is more prone to such panic throttling.
  • There are many other behaviors that I haven't been able to make sense of.

 

It's clear that there are many different systems interacting to create these behaviors. E.g. BIOS controls, embedded controller, CPU self-management, Intel Dynamic Tuning Service, Lenovo Intelligent Thermal Solution Service, Lenovo Intelligent Cooling (fn+T), Windows 10 power management controls...   It is really unfortunate that Lenovo engineering seems to have a policy of not discussion these issues, since they must be in a better position than anyone to say how certain behaviors are triggered, and what combination of settings might affect them. All of this looks like it could be fixed in software, but going by history on this forum that also seems unlikely to happen.

 

This creates a difficult choice. In most ways this is a great machine: best laptop keyboard I've used, other inputs work really well, the (4k) screen is amazing, good expandability, good Linux compatibility. It's a pleasure to work on for coding or photos or design. (The camera is barely ok, but that's not a blocker for my use case.) Performance is very good 97% of the time -- but then a couple of times a day, during critical workflows, it just stops working for a few minutes. Such a shame, it would be an obvious "recommend to buy" if only the user had a way to control this throttling.

 

Not sure what kind of answer I'm hoping for here, but I wanted to at least capture my observations. Personally I'm still making up my mind on whether the benefits are enough to make up for the failings (under the assumption that the throttling will not be fixed).

 

Philipp

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39 Posts

05-31-2021

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  • Posts: 39
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  • Message 2 of 5

Re:P14s gen 2: thoughts and observations on throttling

2021-06-16, 3:17 AM

One more piece to the puzzle:

 

The laptop acts differently when I keep it on my lap (at an angle / moving a bit) vs. when it's flat on a desk. I was... really surprised by that, and didn't want to believe it, but I've been able to repeat it over multiple 10-minute runs. (Cinebench R23, for repeatable and consistent load.)

 

1) When the laptop is flat on a desk, not moving: There's no throttling (with this benchmark at least). First the CPU boosts to full speed for ~30 seconds, then it runs stable and consistently for 9:30 minutes at ~35 Watts. The benchmark results are in line with what's expected for this CPU, a strong result.

 

2) When I keep the laptop on my lap it starts to throttle very quickly. On "best performance" the power immediately drops from 35W to 5W (0.4 GHz). On "better performance", it starts more gradually, but eventually also hits 5W. Either way, it doesn't have time to get hot, so temperature is not the trigger. Benchmark results are much, much worse.

 

Best guess, this feature is supposed to avoid uncomfortable heat when holding the computer. But the end result is that this laptop works very poorly when held in one's lap. Yeah, this was a benchmark, but I saw the same behavior on regular applications.

 

Why is a feature like that not a selectable option in the BIOS?

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39 Posts

05-31-2021

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  • Posts: 39
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  • Message 3 of 5

Re:P14s gen 2: thoughts and observations on throttling

2021-06-16, 23:12 PM

Going through some old threads and news posts, apparently this feature is a part of Intelligent Thermal Solutions. I suppose there were some models in the past that could actually get hot enough to be hazardous. This machine, even when it runs at full load for a while, simply doesn't get that hot, though.

 

My interpretation now is: The Intelligent Thermal Solutions feature is very badly tuned for the current batch of machines. It responds too early (when the machine is effectively still at room temperature), and it responds too aggressively (effectively bringing the machine to a halt instead of reducing power to a sustainable level).

 

I thought I might disable it by stopping the Lenovo Intelligent Thermal Solutions Service; but that just permanently reduces power to a very low level (~10W). I'm also wondering if the BIOS has a part in this feature as well.

 

So I have two requests:

 

1) Please properly tune the feature for each machine, so that even when used on-lap it allows adequate performance. It's not necessary to keep the machine at room temperature. From what I've seen on the P14s gen 2i, running at 20-25W would give good performance, and even in the long run it won't run that hot.

 

2) Please add a dedicated control to the BIOS to completely disable this feature. This laptop is supposed to be a professional tool; so please assume that a professional may be able to judge by themselves if the machine gets too hot, and take appropriate action. (As a BIOS control, this could still be locked down by system administrators if required in a deployment.)

 

Thanks

 

Philipp

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39 Posts

05-31-2021

United States of America

54 Signins

590 Page Views

  • Posts: 39
  • Registered: ‎05-31-2021
  • Location: United States of America
  • Views: 590
  • Message 4 of 5

Re:P14s gen 2: thoughts and observations on throttling

2021-06-17, 16:27 PM

Further details:

 

I'm not sure if this is Lenovo "Intelligent Thermal Services", Lenovo "Cool & Quiet on-lap" (which apparently is a user-controllable feature on some models), or if it is simply part of Intel Dynamic Platform and Thermal Framework (DPTF) or Dynamic Tuning Technology (DTT).

 

What I have found, however, is that if I disable device ACPI\INTC1043 at a Windows system level, the overzealous throttling (based on how the laptop is held) seems to stop. The machine runs at its full capacity (~35W CPU), it achieves best performance, it gets warm, but not too hot.

 

I don't know what other side effects this may have. The CPU has its own thermal protection, which works as expected; but system power management is much more static, and I don't know if other components could be affected by that. I don't think it's good to just disable part of the system like this, but it's the only way I've found to have it run as it's supposed to.

 

At this point I would really appreciate a response from Lenovo. Clearly there's a design defect here, but one that can be fixed in software, since the hardware itself works great. Can we expect a proper solution here (less extreme than disabling the entire device)?

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39 Posts

05-31-2021

United States of America

54 Signins

590 Page Views

  • Posts: 39
  • Registered: ‎05-31-2021
  • Location: United States of America
  • Views: 590
  • Message 5 of 5

Re:P14s gen 2: thoughts and observations on throttling

2021-06-17, 20:57 PM

Results are maybe even better if, instead of ACPI/INTC1043, I disable ACPI/INTC1040: The system still dynamically adjusts power targets. At "best performance" they're set at 35W/64W(boost), which is basically full power for this architecture. Under load it may throttle down to 20W/64W, which still delivers ~90% performance. The system gets warm, but never hot.

 

At "better performance" targets are set at 20W/25W and will throttle down to 10W/25W. That's definitely below what the architecture can deliver (maybe 50% performance?), but everything is still completely usable. The system doesn't even get warm.

 

I have not observed any of the extreme dips to 5W that otherwise happen all the time.

 

There's only so much I can do to debug this as a user. Come on, Lenovo -- can we talk about next steps?

 

Thanks

 

Philipp

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