The LG UltraFine 5K Display Compatibility with 2021 MacBook Pro 14"

I've spent a lot of time investigating this issue and I can comment on compatibility. There are some... issues.

My Setup

• MacBook Pro (16-inch, 2021) M1 Max
• LG UltraFine (27MD5KA-B)
• iMac 27-inch 5K (Late 2015) running Big Sur

What Does Work

The only way I can get the monitor to establish a connection is by first plugging it in, and then turning on or restarting the MBP.

What Does Not Work

• Hot plugging the monitor does not work.
• Connecting through a dock does not work (CalDigit TS3 Plus)
• The LG Screen Manager does not recognise the monitor at all.

Conclusion

To make sure there was nothing wrong with the monitor, I tested it using my iMac and an Apple Thunderbolt 3 to Thunderbolt 2 adapter and Apple Thunderbolt 2 cable. The monitor worked perfectly at full resolution. It was hot-pluggable and the LG Screen Manager also recognised it and checked for firmware updates, which there were none.

So either LG needs to release a Firmware update for Monterey/M1, or Apple needs to update Monterey, or both need to cooperate. In any case, having to restart my MBP every time I want to plug it into the UltraFine is UltraAnnoying.

I am running two LG UltraFine 5K monitors connected to a 2021 MacBook Pro 14 with M1 Max. It works great -- I haven't experienced any problems with sleep, hot plugging, or any other issues. Both monitors are plugged into the USB3 ports on the left side of the computer. It also works with one of the 5k monitors plugged into the right side of the laptop as well, where there is only one USB3 port. Daisy-chaining the monitors does not work -- both must be plugged directly into the laptop.

Hello alexphil,

Thanks for reaching out to us in Apple Support Communities about the compatibility of your MacBook Pro and the LG UltraFine 5K Display. We're happy to help by looking into this more! 

We see you’re coming from the article: Use the LG UltraFine 5K Display with your Mac or iPad. That’s a great article for this issue! It explains which models of Mac are compatible at which resolutions. If you still have questions you can reach out the Apple Sales:

Get Support

Hope this helps.

Best Regards.

As of October 26, 2021, I'm afraid this article isn't updated with information on the 2021 MacBook Pro models with M1 Pro and M1 Max SoCs. I'm curious to know if it's possible to connect dual (or even triple) 5K displays to these machines.

This is not a given for any 2021 MacBook Pro because the LG UltraFine 5K display requires two DisplayPort channels over a single Thunderbolt port. This complicates what is able to connect to these and how many displays can be connected. Typically a machine with four Thunderbolt 3 ports is required, and the monitors can't be connected to adjacent ports because each monitor requires the DisplayPort channels from two Thunderbolt ports.

For instance, even the latest 2020 27" iMac (non pro) can only connect to one of these because it only has two Thunderbolt 3 ports and thus only has enough channels for one monitor. I fear that because of the way the UltraFine 5K works, since the new MacBook Pros only have three ports, only one can be connected (possibly also alongside a single 6K or 4K-or-less display).

Hopefully someone can test this scenario and report back the results!

I have the 2017 MBP 15" (max specs) and 2 LG UltraFine 5K monitors, both running in native 5K resolution, which is being achieved by connecting the monitors directly to MBP using 2 top ports on opposite sides Use the LG UltraFine 5K Display with your Mac or iPad - Apple Support. After reading some of the posts here, I have doubts that I will be able to continue using both monitors in native 5K resolution with 2021 M1 based MBP 16". I'm looking for some information that would help me to make a decision. I'm not looking forward into upgrading 2 LG's with XDR Monitors due to their high cost.

Hey lvit01,

According to the specs, a 2021 MBP should have no problem to run both your LG UltraFines at native 5K:

• M1 Pro supports 2 external displays up to 6K
• M1 Max supports 3 external displays up to 6K + 1 up to 4K

I can only vouch for running one. And the primary issues in this thread are software-related.

But if you want to get away from the 5K’s and buy something with traditional video inputs, there is a comprehensive monitor buying guide over at 9to5Mac.

This is really interesting, OLDsystem. I doubt the problem is with Monterey, because I have an iMac Pro with two of these 5K monitors, and it pretty much works perfectly… I can even hot plug them with no issue.

On the Accidental Tech Podcast, Casey Liss discussed using one of these monitors with his M1 Pro MacBook Pro and it was mostly working, although it developed some issues where the monitor seemed unable to connect reliably over time; the reason was thought to be due to a failing Thunderbolt connector on the monitor.

Given all this, it’s quite strange that you’re having these issues. I wonder if you and Casey Liss are experiencing related issues.

I spoke with LG support, and they suggested it might be an issue with the wake signal not being sent from the Mac when plugging it in, hence the need to restart which works 100% of the time when connected directly (not via a dock).

Once I'm connected I have no issues with the monitor. It has never flickered or given any indication of a loose connection. I have read in several places that the Thunderbolt ports are known to loosen over time. Mine certainly does not feel as sturdy and snug as an Apple-built port, but it also doesn't feel unusually loose.

I expect the iMac Pro to work without problem. It was released shortly before the 5K UltraFines came to market.

But the new MacBook Pros are another story: new silicon, new architecture, new graphics — I would not expect out-of-the-box compatibility. So it may not be a problem with Monterey itself, but more likely a hardware communication issue that can be resolved with a software update.

LG updated their Screen Manager app for M1 early this year, so apparently things should be working for Big Sur on M1 devices. It would be great if someone who has one of the first M1 MacBooks can chime in here.

Update: I was at the Apple Store today and spoke with a very knowledgeable technician. He said they are aware of the compatibility issue with hot plugging. They’ve gotten many reports about it. A software update is planned. He said it will probably also require a firmware update for the monitor. Now we wait.

Of course the terrible irony is that you probably need an Intel Mac to actually be able to update these displays to work on an M1-based machine.

I hope you post an update if and when you are able to solve this!

A little bit of progress: an update to LG Screen Manager was released yesterday. It now recognises when the monitor is connected on the newest M1's running Monterey. However, no firmware update.

I also upgraded to macOS 12.1 and the monitor is still not hot-pluggable.

I have the LG UltraFine 5K displays on my desks at home and work. I'd like to upgrade my laptop to the 2021 MacBook Pro 16" 2021 but I'm hesitating because that laptop ships with a 140W USB-C power adapter and the LG Monitor specs say the "display has one Thunderbolt 3 (USB-C) port which delivers up to 94W of charging power to the host device". That leads me to believe that the display can't power the new 2021 16" MacBook Pro laptop. Does anyone have experience with this new laptop and the LG UltraFine 5K display?

Hi TheMacNut.

Yes, the display can power/charge the 2021 MBP. I have the 1st gen LG UltraFine 5K and the newest 16-inch MBP. It works fine.

The 140W adapter is for the MagSafe 3 connector and is able to fast-charge. But charging can also take place through a Thunderbolt cable, albeit at a slower rate.

Although the stated specifications claim support for 2 (or 3 on the Max) 6K displays, the LG 5K displays use a different technique to connect to the monitors. Apple 6K Pro Display XDR uses display stream compression over a single DisplayPort channel, while the 5K displays each tile 2 displays over a DisplayPort channel, using two DisplayPort channels on a single Thunderbolt 3 connection.

I believe that one of the improvements of Thunderbolt 4 is that each port is now required to support two DisplayPort channels, where before you’d have pairs of ports that would share the two channels. What this meant in practice is that you could connect two displays to the 2016-2019 MacBook Pros with four TB3 ports, but each display had to be connected to another side of the laptop. Similarly, the iMac Pro could connect two LG 5K displays, but you couldn’t use both the left ports or both the right ports, you had to interleave them, basically.

My concern was that this setup wouldn’t quite work on the new laptops, but I believe it will from what I’ve read. I just wish someone would actually try this on the M1 Pro/M1 Max machines and let us know that it works! If someone does attempt this, I’d be interested in knowing if that limitation is gone where you have to plug each monitor in on opposite sides of the laptop.

Thanks Automatt! This is the definitive answer I’ve been looking for. Two LG Ultrafine 5K monitors will work on these M1 Max machines. I suspect they would also work on a lower-end M1 Pro, but it would be nice if someone could also confirm that.