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Question: LG UltraFine 4K‑display + MacBook Pro (13-inch, 2016)

I use my LG UltraFine 4K‑display with my macbook pro solo via usb-c connection.

I don't use some external power supply to my macbook pro.


As soon as i connect the external display my macbook is reacting very slow, perfomance goes down.

Also Bluetooth connections are getting laggy, like my mouse.


I tested some other external display via hdmi connector + external power supply, and the performance is perfect.


I am on High Sierra 10.13.3 (17D47)


I did not test my setup with usb-c connection to the monitor and external power supply, but the reason I got this specific setup was to avoid additional cables and external power supply to my macbook pro.

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Mar 14, 2018 7:48 AM in response to OnlineTexel In response to OnlineTexel

Why do I have difficulty with Wi-Fi or Bluetooth devices when USB 3 devices are attached to my computer?

Some USB 3 devices can generate radio frequency interference that can cause Wi-Fi and Bluetooth devices operating in the 2.4GHz band to have issues communicating with your computer. Here are some tips to avoid this issue:

  • If your USB device has a cable long enough that you can move the device, place it away from your Mac—and make sure not to place it behind your Mac, or near the hinge of its display. The antennas for Wi-Fi and Bluetooth are located there, and USB 3 devices placed there might interfere with your wireless connections.
  • If you're using adapters or dongles on a Mac computer with Thunderbolt 3 (USB-C) ports, plug them into the front port on the left side of your Mac, or into the ports on the right side (if your computer has them). These ports are the farthest away from the antennas, making interference less likely.
  • To avoid interference on the 2.4GHz band using Wi-Fi, try using the 5GHz band instead. You can change this on your wireless base station. Bluetooth always uses 2.4GHz, so this alternative isn't available for Bluetooth.

from:

Using USB devices with your Mac - Apple Support


also, any of these items may be involved:

• Power Adapter cable recall

Apple USB-C Charge Cable Replacement Program - Apple Support

• firmware update for the Apple Multi-Port display adapters (specifically to reduce interference).

About the USB-C Multiport Adapter Update 1.0 - Apple Support

• LG-display recall -- to address Wi-Fi interference so severe, it knocks the Router off the air if too near the Router.

https://9to5mac.com/2017/02/03/lg-fixes-wifi-interference-problems-with-ultrafin e-usb-c-5k-display-new-units-unaffected/


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Mar 14, 2018 7:48 AM

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Mar 14, 2018 8:57 AM in response to Grant Bennet-Alder In response to Grant Bennet-Alder

It is not so much about possible interference, the whole mac is slow.

So even when I don't use some Bluetooth mouse and keyboard the CPU spikes.

So the problem only is there when my external display is connected.

Mar 14, 2018 8:57 AM

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Question: LG UltraFine 4K‑display + MacBook Pro (13-inch, 2016)