So last night I decided to use my iPad as a second screen for my MacBook. I had a YouTube video playing on my iPad screen and was browsing the web on the MacBook screen. After a few minutes I heard my fans kick on (which I have never heard since I have owned my MacBook) and when I launched my CleanMyMacX software and looked it said the temp was 171. Once I unhooked the iPad the temp dropped back down to 84-130. Soon as I hook it up the temp jumps back up. Is this normal?
Just a FYI my MacBook is a 13” 2019 Pro and the iPad is a 2018 11” Pro.
It is normal that the GPU works harder when rendering to 2 or more displays. Modern CPUs and GPUs are fairly economical, when they are powering one screen. But adding extra displays can more than double the power consumption of the GPU. It isn’t therefore surprising that the processor runs hotter (integrated graphics). Also don’t forget, you now also have 2 applications running in the foreground, so both applications are having to have more processor time to render their images as well.
If anything, it shows that the MacBook is optimized for a “light load” in its heat dissipation concept. Once the heat builds up from doing more work on the processor (display YouTube and another browser window) and the GPU having to twice as much rendering, the passive cooling capabilities of the Mac design reached and the fans have to spin up to get rid of the extra waste heat.