If your MacBook Pro overheats, you might be charging it from the wrong side

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It takes years of professional training to place MacBook stickers this badly.
Even the new-ish 16-inch MacBook Pro runs hot.
Photo: Charlie Sorrel/Cult of Mac

Does your brand new MacBook Pro go into meltdown when it’s plugged into power? Do the fans spin up into a blast of white noise, while the heat makes your hands sweat as you type? Is your kernel\_task pegged using 100% of the CPU when you check things out in the Activity Monitor app?

If so, don’t worry — it’s not your Mac’s fault. It’s you. You’re charging it wrong.

Yes, if you plug your USB-C power cable into the left-hand side of your MacBook Pro, you might make it overheat.

Right isn’t wrong

It appears that some MacBook Pro models are more sensitive to heat on their left side than they are on the right. If you plug the power cable into the “wrong” side, the increased heat caused by charging may trip the temperature sensors, and send the fans a-spinning. This Stack Exchange thread discusses the strange situation, with this post from user Bmike detailing the steps that can be taken to induce and mitigate the problem.

The thermal panic seems to be triggered by too much happening on the left side of the MacBook Pro. If you plug in power as well as other Thunderbolt or USB-C peripherals, things get hotter. Then the Mac takes measures to cool the machine.

But why on the left side? Is it that things actually get hotter over there? Probably not. It seems that the sensors on the left are more sensitive, or at least are more likely to trigger heat-reducing measures.

kernel_task

So what about the kernel\_task process that shows up in your Mac’s Activity Monitor app, pegging a CPU core at 100%? Isn’t this runaway process responsible for the increased heat? How can you kill the kernel\_task?

The answer is, you can’t — and you don’t want to. You can force quit the kernel\_task, and it will come back. Even a reboot won’t make it stay dead. That’s because the kernel\_task is a response to the extra heat, not the cause of it. You no more want to stop the kernel task than you would want to drain the water from your car’s radiator if its engine was overheating.

Howard Oakley, writing for the Eclectic Light Company blog, details the process in his article, “Why is kernel_task eating my CPU?” In short, if the kernel task ramps up, and your Mac’s fans spin out of control, you should try to help it cool down. Stop any intensive tasks, make sure the airflow around the machine is good (no cushions or soft neoprene cases under it, for example), and let it cool off.

How to stop your Mac overheating

This is clearly ridiculous — a pro-level machine should be capable of running pro-level tasks for extended periods. And it’s especially absurd because “charging your Mac” isn’t really considered a pro-level task, so it shouldn’t even be on a user’s radar. But here we are, with Intel’s hot, power-hungry chips stuffed into Apple’s undercooled, too-thin computers.

To avoid meltdown, charge your Mac from the right-hand side, especially if you have other devices plugged into its other ports. And if things do get too hot, take a break, and let your multi-thousand-dollar professional computer take a break.