Apple may have a new Chargegate on its hands from the looks of it. Several users have found that their MacBook Pro uses the left side ports to max out the CPU and overheat while charging.
Apple states on its official support page that you can charge your MacBook Pro using any of the USB-C ports. But it turns out there’s a right way and a wrong way to charge your expensive computer, particularly if you don’t want to see any effect on results.
A StackExchange user who mentioned seeing suspicious behavior in the Activity Monitor noticed the problem some months ago. Specifically, he found extremely high CPU usage for a process called kernel task, which triggered high temperatures and decreased overall device efficiency-not to mention the fact that it keeps those tiny fans spinning on what otherwise should be a fairly quiet computer.
If that wasn’t enough, restarting the MacBook in question won’t fix the problem, as soon as macOS boots up, the kernel task process pops up again. According to Apple, one of the kernel task’s tasks is to control the CPU temperature of your MacBook by intentionally making less of it accessible for applications that use it too heavily.
In this case, a careful investigation revealed that the temperature of the MacBook case is increased by having a peripheral plugged into one of the left ports at the same time as a charger is connected to another. Sensors tracking the Thunderbolt ports tended to confirm this is the case even though the temperature of the CPU does not warrant the throttling.
Fortunately, there’s a easy solution to this, and it’s charging your MacBook using just the right-hand side ports without avoiding the left-hand peripheral ones. Another Stackexchange consumer indicated that this technique could apply to plugging monitors on a different side to keep things cool on both sides of the frame as the charging cable.
Two models appear to be affected at this point: the 2017 MacBook Pro 15-inch, and the 2019 MacBook Pro 16-inch. Apple has yet to comment on the issue, but at least we know the company is working on the next macOS Catalina update to extend the lifetime of the MacBook batteries. Hopefully, it will also provide a workaround to the heat problems associated with charging it using the left side ports.