Connect a Thunderbolt display and a DisplayPort display to the same MacBook Pro

I'm trying to connect the old generation LG UltraFine 4k Display (USB-C DisplayPort) and the old generation LG UltraFine 5k Display (USB-C Thunderbolt) to a 13" MacBook Pro from 2019 (with 4 Thunderbolt 3 USB-C ports).

Here's what works:

• If I connect just the 5K display through its Thunderbolt USB-C cable, it works fine.
• If I connect just the 4K display through its DisplayPort USB-C cable, it works fine.

Here's what doesn't work:

• I can't seem to daisy-chain the 4K display of the 5K display as there's no incoming DisplayPort/Thunderbolt port on the 5K display.
• If I connect both displays to the MacBook using two different ports, it just registers and uses the one I plugged in first.

I suspect that the Mac somehow either can't handle or don't understand running both Thunderbolt and DisplayPort at the same time - but maybe it's a configuration issue? I haven't been able to find anything online about this.

Solution 1:

Your model MacBook Pro can power external displays at 60Hz in the following combinations:

• One display at 5120 x 2880 resolution with over a billion colors
• Two displays at 3840 x 2160 resolution with over a billion colors
• Two displays at 4096 x 2304 resolution with millions of colors

So, to use both the 5K and 4K displays you need to be mindful of the resolution they're each at. To change the resolution:

1. Since you're trying to use a 5K display and a 4K display, I'd start by only connecting the 5K display first, preferably in one of the left ports
2. Go to Apple > System Preferences... > Displays
3. Make sure the Display tab is selected
4. Select the Scaled radio button
5. Now choose one of the scaled options that appear below (Hint: You can view the selected pixel dimensions below the image of your display on the left)
6. Once you have your display set at 4096 x 2304 (or below), exit System Preferences
7. Connect your 4K display to one of the right ports
8. Now go back to Apple > System Preferences... > Displays
9. Make sure the Display tab is selected
10. Now hold down the option key to see the additional scaled options for the second display
11. Now choose one of the scaled options for the 2nd display
12. Exit System preferences

See the screenshot below for reference:

REMINDER: If you're wanting to use billions of colours, then at Steps 5 and 11 you need to set your resolution at 3840 x 2160 or lower. Otherwise, if you're happy to use millions of colours, you can set the resolution for each display as high as 4096 x 2304 each. Keep in mind the actual resolution choices you get will depend on your displays and the adapters you're using.

Let me know if you're still running into problems and we can troubleshoot from there.

Solution 2:

Apparently, the MacBook Pro can only power external displays up to 5K resolution. What you can do to use both the monitors is: Connect one of the monitors (preferably the 5k first) and lower it's resolution way down, up to 720p perhaps, by following the steps as illustrated in

https://support.apple.com/kb/ph25175?locale=en_US

Then connect the other monitor(4k), now the combined resolution is below/equal to 5k, depending on your adjustments.

Now adjust the resolutions on both the monitors to suit your needs, while you do take care that the combined resolutions don't exceed 5k. Unfortunately, you will have to make some compromises with the resolutions with both the monitors.

I personally haven't tried this out as I don't have the hardware available, so do tell me if it works.