Ask HN: How is my MacBook temp getting misread?

3 GWBullshit 4 7/15/2025, 2:01:32 AM

Ever since the last MacOS update, my MacBook has been overheating very easily, very often. When this happened in the past, I would simply put it in the freezer for a few minutes and then pull it out and get back to work. Now something strange is happening: The MacBook itself will be ice-cold, but unlike before when it would just resume working wonderfully, now it "sort of" works, but not really. For example synching stops and says "It needs to wait until the temperature drops". I installed an app to see what's going on and it's reading the CPU at 190º+ F and the GPU at 200º+. Why? How could anything inside be that hot when the frame itself is ice cold?

Comments (4)

apothegm · 5h ago

The metal frame of a MacBook is part of the cooling apparatus. If something in the heat conduction chain got messed up (see the earlier comment about freezers and thermal paste), the chips are unable to shed their heat into the frame the way they’re meant to. Keeping the frame cooler than usual, while the chip quickly overheats.

_wire_ · 4h ago

A fissure in the thermal bonding compound between the chip and the heat spreader, or a loose heatspreader anchor screw causing the spreader to lose fit to the chip. Either can result from a fall or other shock, or a manufacturing defect.

leakycap · 6h ago

MacBooks are metal. When you put them in the freezer, the likelihood of moisture damage, especially around very hot components, is much higher than if you try this with a plastic electronic device. I wouldn't put metal laptops in the freezer, as damage to small sensors could be your issue. In fact, anything with thermal paste really shouldn't go in the freezer. But too late to undo that, you can stop doing it though.

The way macOS/ firmware handles cooling can be confusing. Have you tried rebooting in single user mode and checked the temps from there? Have you ran the hardware diagnostics from boot?

aurizon · 5h ago

open up, remove heat sinked parts, clean both faces with isopropyl alcohol. Buy some 'cooler master' paste and reseat. Take care with minimal alcohol and power off - it can catch fire. Most repair shops can do this - ask first

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