I just replaced my 6 year old MBP with a new 16" MBP which requires the addition of adapters to connect just about anything external. So I got a USB-C hub with HDMI, RJ-45, USB-3.1 and SD card connectors. If it helps, it is from Networx, model no. Y-9115-S. It works, but gets ridiculously hot (40 - 50˚C) with only a USB stick or an ethernet cable plugged in.

No, I am not running ffmpeg on the hub's internal processor.

This happens with the hub on both the left and right side ports. It comes with its own power supply but I don't use it and run the hub unpowered. The hub temperature certainly is a design flaw in a first-generation product, but I wonder if it is normal. Have others experienced the same or is my hub defective?

  • Talking about design flaws – that hub comes with an external power supply. And is meant as an accessory for a portable computer. What were they thinking? Dec 13, 2019 at 9:28
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    I think it's a good sign: heat dissipation works comparing two SanDisk thumb drives with an equal size and power consumption & both attached to an iMac - one in a plastic the other one in an aluminum enclosure. The one made of aluminum is also very warm (~50°C), the other one is lukewarm (physics!), but I don't really wanna know how hot it is inside....
    – klanomath
    Dec 13, 2019 at 13:09
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    @klanomath: That is scant comfort for the fact that this thing is converting my battery's energy to heat faster than the computer itself. And just for some signal conversion. Dec 13, 2019 at 13:46
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    @PeterKämpf How much power does it draw while in use? (🍎 > About this Mac… > System reports... > Hardware > USB (probably))
    – klanomath
    Dec 13, 2019 at 13:51
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    Two words: cheap components. See this answer for a similar scenario. This is normal
    – Allan
    Jan 8, 2020 at 11:55

1 Answer 1


As usual, the flood of different converters uses only a few board designs, and the most popular one seems to use cheap components, most likely for power conversion from 5V to 3.3V for its internal electronics. A step-down converter (similar to a switching power supply) costs more than converting the excess voltage to heat via resistors, after all.

I have now found a product made by iTeknic (model # IK-UC001) which actually carries a warning that it might heat up to 130 F in use, but so far it has stayed cool in tasks where the other adapters would heat up close to those 130 F. I have not looked inside (yet) but suspect it uses a step-down converter. They cost about 0.1% of the hub's purchase price, after all.

I guess the Networkx hub's external power supply (for a device meant for portable use!) should had been a warning. The iTeknic hub comes without such a power supply.

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