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My 2018 macbook pro with i9 processor running Catalina version 10.15.6 seems to randomly throttle the CPU frequency even with low CPU utilization and lowish temperatures: enter image description here

I am using a docking station to connect to two external monitors and received hard wired ethernet. Additionally, I'm suppling power via the default usb c apple charger. I read in some places that this throttling could maybe with a bad power source, so I connected the default charger.

Any insight here? I updated to Catalina recently, but the problem existed before the update and has happened after as well. Does it have to do with my docking station? Hardware problem? The frequency throttling seems to happen even after I unplug the docking station, but I never really use my computer enough without the docker station to notice if it happens during normal use.

Here's output of pmset -g thermlog

enter image description here

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    It looks like you're using an old version of Intel Power Gadget. Is it possible that the graphs are misleading? Or were you experiencing slow-downs and then got Power Gadget to see what's going on? (In the version of Power Gadget I have (3.6.0), the Frequency has both requested and actual values.)
    – Wayne
    Commented Sep 4, 2020 at 14:27
  • I'm experiencing serious slow downs AND kerneld is taking 600%+ CPU in activity monitor. I then got power gadget to see what was going on. I couldn't find the most up to date install, so I went with an older one.
    – Andrew Cassidy
    Commented Sep 8, 2020 at 14:54
  • Mac laptops are synonymous with heat problems, sadly.
    – Tulains Córdova
    Commented Sep 14, 2020 at 21:54
  • @TulainsCórdova my temperature is low
    – Andrew Cassidy
    Commented Sep 14, 2020 at 23:15
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    @n1000 yeah fans are usually at full speed. I played around with it a bunch more and it 100% seems like it's the docking station. I'm switching to plugging all monitors and ethernet into the computer itself to see if that helps. Thanks for all your knowledge and suggestions. I have a feeling the docking station is crap. What's weird is that it worked with the docking station for a very long time.....
    – Andrew Cassidy
    Commented Sep 15, 2020 at 22:51

2 Answers 2

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In my opinion you are not seeing CPU throttling, but one of Intel's power saving features known as Dynamic Frequency Scaling or more specifically Intel SpeedStep. While idle, the CPU can dynamically reduce clock speed to reduce power consumption.

CPU throttling only occurs if certain constraints are reached, such as high temperature or power consumption. Judging from your figure neither are the case. Also it is practically not possible to tell if CPU throttling is occurring from your screenshot. Please see my question here on how to identify throttling on MacBooks: How to monitor and control thermal CPU throttling in OS X?

In case you still think you are experiencing CPU throttling, I suggest you update your question with the output from pmset -g thermlog as described in the accepted answer or update your screenshot with one from the latest Intel Power Gadget where the REQ parameter gives you an indication of throttling.

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  • My CPU isn't idle though (at least in the screenshot)? Additionally, this seems to happen when using FaceTime or any other application that takes up CPU. I have run pmset =g thermlog and seen throttling in the past, but I'll monitor it now more often. Is there a way to turn off dynamic frequency scaling?
    – Andrew Cassidy
    Commented Sep 14, 2020 at 18:39
  • @AndrewCassidy In your screenshot the CPU is far from busy with a load of 35% ;-) You would see hardly any to no performance gains and increased battery drain if the clock speed would remain always at the maximum. SpeedStep is optimized to very rapidly change the clock depending on the current load situation. Some Windows PCs allow to tweak this and I wouldn't be surprised if macOS also has different settings depending on whether the Macbook is connected to power or not. There may be a way, but I wouldn't recommend it at all: apple.stackexchange.com/q/116193/45492
    – n1000
    Commented Sep 14, 2020 at 18:57
  • I've added a screenshot of the pmset output to my original post.
    – Andrew Cassidy
    Commented Sep 14, 2020 at 21:16
  • And to update. It does this randomly all the time when I'm trying to use my computer (with CPU use spikes up to 50%) and just creates a laggy experience on my end.
    – Andrew Cassidy
    Commented Sep 14, 2020 at 21:30
  • @AndrewCassidy OK. This is odd indeed. MacBooks do throttle heavily if not enough power is available or battery is very low. It would be good to have more data on your issue. What was the load when throttling occured? Can you install the latest Power Gadget, e.g. using homebrew and update the screenshot?
    – n1000
    Commented Sep 14, 2020 at 21:43
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Any insight here?

You're unfortunately dealing with a long standing problem Apple has had with trying to jam a Core i9 CPU into a form factor that is inherently and notoriously bad with respect to thermal design.

Here's just a short list of articles addressing this issue.

A pragmatist perspective...

Apple claims to have issued a software patch. It wouldn't be out of the ordinary for Apple to break things again with a macOS update. How many times has an update broken something like WiFi only to be fixed in the subsequent release?

Even with a software patch, you can't get around physics. IMO, there's an unreasonable expectation when it comes to MacBook Pro computers: users want them to be razor thin, completely silent, and über powerful. Unfortunately, physics has a bad habit of crashing the party.

If you want all the power of a high end CPU and GPU then you have to deal with the heat it generates. Dealing with heat means cooling - proper heat sinks and fans. That alone has a balance you must strike - if you want proper cooling but have something be very quiet, you need larger heat sinks. If you want something razor thin, thereby limiting the size of the heat sink, you need a fan which inherently makes noise. So, if the market is demanding a razor thin, silent laptop with an i9 processor and GPU, then the trade off will be thermal throttling.

So, to answer your question, it's a design problem with that form factor and it's not limited to your MacBook Pro - other manufacturers are dealing with this issue.

From a personal perspective, I wouldn't get a MacBook with an i7 or i9 processor because it just doesn't have the size heat sink required to efficiently dissapate heat. The fans are also to anemic to efficiently cool things down. This means it has to throttle to limit heat which means you're not getting the CPU you paid for. To put it another way, I would rather have an i5 that can run at 100% with no throttling than an i7 or i9 that can only run at 50-75% because of throttling.

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  • I guess I'm surprised since the patch was shipped a long time ago. As well... my temperature on my power meter isn't very high?
    – Andrew Cassidy
    Commented Sep 10, 2020 at 16:29
  • I saw also a new in other post, it seems more like a problem created by Intel. pcmag.com/news/…
    – elulcao
    Commented Sep 13, 2020 at 3:31
  • While I agree that the MBP envelope is not sufficient to handle the i7/i9, I don't think OP is experiencing thermal throttling. Have a look at the CPU load and temperatures in the screenshot.
    – n1000
    Commented Sep 14, 2020 at 10:18
  • @n1000 - that screen shot isn't showing what the OP is describing - it's not relevant to the question.
    – Allan
    Commented Oct 4, 2020 at 16:53

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