Thermal Problems with MacBook Pro 2016

[Chris Pink]

I am having issues with my MBP 2016. Mojave 10.14.6

I can't run the charger and an external monitor at the same time without CPU limiting.

I am monitoring with Terminal pmset -g thermlog The ambient temperature is around 27°C.

If I have the charger and a monitor at the same time, even at startup, the CPU_Speed_Limit kicks in and settles pretty quickly at 26% CPU_Scheduler_Limit at 40% and fans at full speed.

If I charge fully and run on battery then I can run the 2nd monitor. I have a thunderbolt display and a portable USB-C display and the issue is the same with both - this issue started after I was using both at the same time but is now with either one plugged in.

I have the MacBook with the back raised so that the vents are clear, it's on a solid desk and pointing an external fan at the back has no effect.

Following articles from the internet I have varied the ports used - left / right to no effect. I have also reset the SMC, [shift-ctrl-option power 10 secs release, restart].

So, two questions.

1. How do I know the SMC reset was successful, there's no feedback?
2. What else can I do to diagnose or resolve the issue?

 

[jav6454]

Have you opened your Mac and checked if the internal fan is clean or the airflow path is clear?

 

[Chris Pink]

Have you opened your Mac and checked if the internal fan is clean or the airflow path is clear?

I have but the problem seems less related to actual heat and more to use, ie this morning I started the computer, it's on charge, as soon as I plugged in a monitor the CPU_Speed_Limit started dropping, there was no increase in fan speed.

I guess another supplementary question is what monitoring tools can I use to find out what is triggering the CPU throttling?

 

[jav6454]

Unsure from my end.

 

[Chris Pink]

I'm now monitoring temperature with XRG and this is the situation just after startup this morning with charger in one side, monitor in the left. As you can see there's no excessive temperatures.

What else can cause CPU limiting?

 

[Jack Neill]

. What else can I do to diagnose or resolve the issue?

Backup and reinstall macOS and/or dual boot with a newer/clean install of macOS to see if the problem persists to identify if its software or hardware.