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Macbook Pro 2017 13" + RX580 CPU Clock Fluctuations
 

Macbook Pro 2017 13" + RX580 CPU Clock Fluctuations  

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rickypiola97
(@rickypiola97)
Active Member
Joined: 1 year ago
 

Hi everyone,
I managed to get my setup to work in bootcamp:

but I have a weird CPU Clock Fluctuation issue, and I'm not even sure it's related to my eGPU but I hope you will still be able to help me 🙂

First of all I have to mention that I use Throttlestop to unlock my CPU's boost frequency and have it run at 3.5GHz, otherwise it wouldn't go past 3.1GHz, and I also use "Macs Fan Control" to make it so the PC runs a little bit cooler under load (Now it never goes past 85°C pretty much)

Now to the actual problem:
The problem is summarized in this image: https://imgur.com/a/JD0jj12

The graph has 3 distinct phases:

  1. 3.5 GHz stable - I was in Fortnite Main menu
  2. 399 Mhz stable - This just happens kinda randomly when I'm playing most of the time, but this time the drop looked like got triggered from me Alt-tabbing to Discord. The computer at this clock speed is obviously barely responding and completely unusable
  3. 3.5 Ghz to 399 Mhz Fluctuations - I think at this time I was closing the game, when this happens in game it super annoying since the frame rate, obviously, heavely fluctuates as well
  4. 3.1 GHz to 3.5 Ghz - This is normal. At this point I had closed the game and started Heaven Benchmark and therefore, since it's not very CPU intensive, the clock speed usually goes up and down between "base" and "boost".

This was just one instance of the problem that happened to me today but usually it happens when I've been playing for 1 or 2 hrs and you notice it since the fps start to drop in intervals (Phase 3) and the it becomes completely unusable (Phase 2).

The obvious anwer would be Thermal Throttling, but I really don't think that is the problem since the CPU never actually goes past 85°C and usually sits at around 75°C, and even if that was the case, reducing the speed to a mere 0.4GHz is way too aggressive of a throttling.

I should also mention that I'm running the latest version of Windows with apple_set_os.efi on rEFInd. The windows bootcamp installation is some 3 months old while I've had the eGPU since only a week (when I got the eGPU I also installed rEFInd and applied the mentioned "CPU tweaks").

Hope you can give me some ideas on how to fix this.

Pending: Add my system information and expected eGPU configuration to my signature to give context to my posts


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Eightarmedpet
(@eightarmedpet)
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Joined: 2 years ago

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rickypiola97
(@rickypiola97)
Active Member
Joined: 1 year ago
 
Posted by: Eightarmedpet

How did you get past error 12?

I initially tried to make it work without rEFInd and apple_set_os.efi but couldn’t get past error 12.
I tried hot plugging as soon as the windows logo appeared but the display glitched out, I tried disabling the right TB ports and camera but nothing worked. 

So I followed the procedure in this guide with a little bit of changes in the rEFInd install procedure. (Nothing significant though). 

Now I don’t get error 12 unless I hotplug and I can even use all my TB ports.

This post was modified 9 months ago

Pending: Add my system information and expected eGPU configuration to my signature to give context to my posts


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nanoBit
(@nanobit)
Trusted Member
Joined: 2 years ago
 

The 3rd phase looks like thermal throttling. Look at discussions about the 2018 model when it was released, the graphs looked exactly like yours. When it gets too hot the MBP throttles down to a minimum speed of a few hundred MHz until it's cooled down a bit (which usually takes less than a second), that's typical MacBook behavior. 
Since you said it happens after some time of usage... did you check the temperature of other sensors, too? I could imagine the MacBook heats so much up that not just the CPU temperature is causing the thermal throttling but other parts, too. Since the 13" model has just a single fan the cooling capacity is much worse than 15" models.

If it's not thermal throttling of the CPU my guess would be the power consumption. Do you know how much power the CPU needs at 3.5GHz? Usually more power = more heat, especially in the transformation parts. In the Mac the power board is responsible for that. I'm not an electrical engineer but I could image it heats up when it has to deliver more power than it was built for. 

I'd suggest to try it without the CPU tweaks. The limits are there for a reason. If it works then you got your answer, if not we got to think about other possible solutions 😅

Setup: MacBook Pro 2018 15" 2.6GHz Radeon Pro 560X on macOS 10.14 & Windows 10 (Bootcamp); Sonnet eGFX Breakaway Box 350 with a Zotac GTX1080 AMP! Edition


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rickypiola97
(@rickypiola97)
Active Member
Joined: 1 year ago
 
Posted by: nanoBit

The 3rd phase looks like thermal throttling. Look at discussions about the 2018 model when it was released, the graphs looked exactly like yours. When it gets too hot the MBP throttles down to a minimum speed of a few hundred MHz until it's cooled down a bit (which usually takes less than a second), that's typical MacBook behavior. 
Since you said it happens after some time of usage... did you check the temperature of other sensors, too? I could imagine the MacBook heats so much up that not just the CPU temperature is causing the thermal throttling but other parts, too. Since the 13" model has just a single fan the cooling capacity is much worse than 15" models.

If it's not thermal throttling of the CPU my guess would be the power consumption. Do you know how much power the CPU needs at 3.5GHz? Usually more power = more heat, especially in the transformation parts. In the Mac the power board is responsible for that. I'm not an electrical engineer but I could image it heats up when it has to deliver more power than it was built for. 

I'd suggest to try it without the CPU tweaks. The limits are there for a reason. If it works then you got your answer, if not we got to think about other possible solutions 😅

Yeah, it’s definitely got something to do with the tweaks. I was playing just now and experienced the same situation as I described.  So I quit “Macs fan control” and the fan started spinning really fast for like two seconds and then the clock speed stabilized. I’ve now been playing for an hour and experienced no problems. 

It’s feel kinda dumb not having tried that before posting this, it’s just that I always keep an eye on the CPU temps and really didn’t think those were a problem.
And it’s not like the fans now spin faster, actually it’s quite the opposite!

About the power consumption thing: I really don’t think that would be a problem, the processor is rated at 28W because it has an Intel Iris iGPU but I don’t use it while in Windows (I even turn off the laptop display) so the cpu draws 22W max (@3.5GHz)

Thank you very much for the advice and I’ll keep on testing to see if it’s actually fixed.

This post was modified 9 months ago

Pending: Add my system information and expected eGPU configuration to my signature to give context to my posts


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nanoBit
(@nanobit)
Trusted Member
Joined: 2 years ago
 

Well there are always 2 ways for a computer to cool the CPU down... lowering the clock speed and/or higher fan speed. In my opinion at least one of both possibilities should be handled automatically. If you control the fan speed the MacBook has a fixed cooling capacity. If this capacity is exceeded, the clock speed will be lowered. So if your CPU's temperature is ok does not mean that it's capable to offer maximum performance, it can still be slowed down by the firmware. 

If you seek for higher CPU power of your Mac, did you try undervolting? It lowers the CPU temperatures, which could help you. Just be really cautious and read through guides before doing this, if you undervolt your CPU too much you could crash your system.

Setup: MacBook Pro 2018 15" 2.6GHz Radeon Pro 560X on macOS 10.14 & Windows 10 (Bootcamp); Sonnet eGFX Breakaway Box 350 with a Zotac GTX1080 AMP! Edition


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rickypiola97
(@rickypiola97)
Active Member
Joined: 1 year ago
 

Yeah I’ve been thinking about undervolting to get as my performance as possible out of my CPU.
The thing is that nothing is gonna change the fact that  it is a low power dual core so I’m probably gonna end up upgrading to a 2018 model or a 15”.
On this matter how do you think the following systems compare for egpu:

From what I gathered the 2018 models have a hard time reaching high frequencies due to their high core count. Could the best option be a 2017 15inch (also considering they cost quite a bit less). I’m talking strictly about gaming performance since it’s the most demanding task I do on my pc. 

Pending: Add my system information and expected eGPU configuration to my signature to give context to my posts


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nanoBit
(@nanobit)
Trusted Member
Joined: 2 years ago
 

Generally speaking a MBP without a dGPU is ways easier to use with an eGPU than one with a dGPU. I don't know which games you're playing but most of the ones I play (Destiny 2 for instance) require not that much CPU-power. 
I got a 15" 2018 MBP and I love it. The performance issues of their first weeks are gone. Yes, they barely use the boost speed, but it's not that important. Since it has 6 cores I never needed the boost. My 2018 MBP was almost plug and play. The only issue I have is that the internal screen stays black using the eGPU in Windows, but there's a fix for that, too (turning the dGPU off).

If you consider a 2017 model watch for the PCI configuration of the CPU. In contrast to the lastest models, the 2017 13" MBPs used a 4x PCI lane for all 4 Thunderbolt ports, which can lead to performance issues. Especially in Bootcamp I struggled a lot with my old 13" MBP because Apples firmware did not offer a "Large Memory"-Connection, which is needed to run an eGPU. Read a bit through the forums here, there are lots of build guides and discussions how to get Large Memory and fix Error 12 in Windows.

Setup: MacBook Pro 2018 15" 2.6GHz Radeon Pro 560X on macOS 10.14 & Windows 10 (Bootcamp); Sonnet eGFX Breakaway Box 350 with a Zotac GTX1080 AMP! Edition


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