I have a MacBook Pro M4 with 16GB of RAM running MacOS 15.6.1, and I've noticed a strange smell that resembles a hair dryer when the laptop is under heavy load. It's a faint smell that I can only detect by putting my nose close to the exhaust vent. The temperature stays normal, below 100°C, and I've had it professionally diagnosed twice. Each time, they found nothing wrong after opening it up and cleaning it. They even suggested replacing the motherboard, but again, they couldn't find any issues. Has anyone experienced something similar?
4 Answers
Could be some dust build-up. While 100°C does seem a bit hot for a Mac, it’s not too uncommon under heavy load. I’d expect it to be closer to 90°C-95°C instead.
What you're smelling could just be hot air. CPUs vent hot air to cool down, and that alone can produce an odor—similar to how a hair dryer works when it's blowing hot air.
If your MacBook is old, the thermal paste might be drying out, which can also give off a smell. Just something to consider!
It might just be plastic or paint emitting fumes due to the heat. High temperatures can sometimes cause materials to give off a smell, especially when they're under load.

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