M1 Max and LG 5K2K monitor - Failure

Well, after a few weeks of trying, I am giving up on getting LG’s 34" 5K2K monitor to work with my shiny M1 Max MBPro (32GB, 24 graphics core).

The MBPro just doesn’t work reliably with this monitor. I am uncertain if it is the MBPro or the monitor, but from what I have read online I suspect the Apple ARM processors are just not production ready for this type of monitor.

When I first got it, I plugged it into the TB3 port on the right side of the MBPro (where there is a single TB3 port), and oddly it was detected at a lower than full 5K resolution and in addition system information said there was a second monitor connected - which there was not.

I was able to get it working at full resolution by connecting to the other side of the MBPro, and for the past two weeks or so it has been working fine with the MBPro remaining docked and connected to it (via the OWC TB4 hub). Yesterday I also hooked up my older LG 27" 4K as a second external monitor and all was fine.

Today when I woke the MBPro from sleep, the 5K is detected at a lower res. In Displays preferences, asking for scaled resolutions (even with the option key held down) does not show the full 5K as being available. Multiple reboots with and without the monitor connected, plugging and unplugging, plugging in directly (without the hub in the connection path) - no luck.

Oddly, if I have the MBPro open and not in clamshell mode it seems to detect the 5K correctly, and if I have the MBPro in clamshell and connect BOTH the 4K and the 5K, both are detected correctly. The 4K works fine no matter how it is connected and how the MBPro is set up (clamshell or open).

I tried DisplayPort 1.2 and 1.4 as there were some comments online that it worked with 1.2 but not 1.4 (note I already had it at 1.2 when this whole thing started) and still it is so unreliable that I simply cannot work with it.

I suppose there may be an eventual fix for the MBPro (Apple apparently stated a fix would be out in December 2020 (not a typo on the year) but everything I read online indicates this is still in issue). There is an out called BetterDummy that supposed fixes this by creating a “dummy” display and mapping it to the real display, but I don’t want to have this much money (nearly 1200) invested in a monitor that may or may not work at any given time.

So, unfortunately, I have to commit to shipping it back tomorrow while still in the return window.

Sadly, there seems to be NO high res monitor out there that works properly with the M1 Max at this time, beyond the Apple ProDisplay XDR. Although I am eligible for educational pricing, this display with the VESA mount is still going to hit $5000+ after tax, and that just isn’t a justifiable expense for me. Even the rumored upcoming new Apple monitors are projected to come in at about 1/2 the cost of the XDR, and it’s hard to justify even $2500 at this point.

I would think Apple could really sell a lot of units if they could get a high-res (eg 5K) larger format (32-34") monitor onto the market that worked reliably with Apple silicon and came it at a consumer-affordable price.

Did you try Apple’s LG UltraFine 5K Display? I don’t see that mentioned in your post.

I use a Samsung 28" 4K with my M1 Pro and it works absolutely flawlessly. Not a single issue.

I don’t know if there is a difference in the monitor controller between Pro and Max though.

@karlnyhus : No, I didn’t try the LG 5K ultra fine…it’s 27”, and I was really going for a larger sized monitor, which is why I bought the 34”. That’s a great question, though, in that I would expect that monitor to be supported since it is sold by Apple, which makes it odd that my MBPro cannot properly handle a different 5K monitor also made my LG.

@Rob_Polding : Yes, my LG 27” 4K also works just fine….it makes me wonder if the issue is the MBPro or the monitor…But I am not sure how to figure that out.

It’s definitely the monitor interacting with macOS. The 5k2k also required complicated workarounds and specific cables on Intel machines. I think returning it is the right decision. It’s a bummer that LG and Apple can’t work together to figure out support for nonstandard resolutions.

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It’s really too bad because there are so few high resolution options, and really only this one in Ultra Wide.

I desperately want an Ultra Wide, but coming from an LG 5k, 5k2k is really at the bottom of what I’ll accept as far as pixel density. Some day…

Are you running it via TB3 to TB3?

If so, try a TB3 > DisplayPort cable instead and see if that works more stable. The emulation to DisplayPort might be all it needs to overcome Thunderbolt chip inconsistencies.

Alternatively, try an HDMI cable as well …

@cornchip : Thanks. That’s what I’ve been seeing online, with reports going back over a year, and no clear resolution. I really wanted a high-res screen over 30”, but I don’t think that’s in the cards given that I am not going to spring for the XDR at this point.

@thickweb : I agree; I would have preferred 6K in this screen size, but again that means the XDR …

@simonsmark : I thought about trying that, but did not given that that eliminates the advantages of a TB3 connection (eg the built in hub, etc). However, since I am using an OWC TB4 hub anyway, I could live without the built in hub or use the upstream USB connectivity, so I will give this a try tonight. I am not optimistic, but if it works that would make me happy - or at least less unhappy.

I do have a 38” Viewsonic on order, not yet shipped. It’s a lower resolution so I am optimistic it will work. I can use my 27” 4K (which does work) for the fine points of photography editing and the 38” for general work, but I really wanted the higher resolution of the 5K….

@simonsmark : Well, you called it! Many thanks.

I hooked up via a TB3 to DisplayPort cable last night, and so far it works just fine.

I assume there is some problem with TB on either the M1 Max chips or the LG monitor. I’m going to assume (hope) the latter….

The problem seems to somehow relate to the way the monitor provides resolution information to the Mac. This LG 5K2K has a feature where you can have it incorporate two different video inputs into a picture by picture mode, dividing the screen either into 1/2 sections or a 2/3 + 1/3 section. Obviously the pixel count is lower when you are, for example, feeding an input into 1/2 the screen, 2/3 of the screen, or the entire screen.

Via TB, if I feed the TB input into a 1/2 or 2/3 screen, it works fine, the image is beautiful, and the MBPro recognizes the provided pixel count. When I feed in to the full screen, it fails to handle the full 5K pixel count, and while previously it would show an image at a reduced resolution (which was unusable blurry, btw), now it just flashes the screen and goes back to black (I have no idea what changed when I had this working previously, btw, unless the TB port on the monitor is actually defective).

Via TB to DisplayPort I can see the full 5K full screen resolution and it looks fantastic. Since I can live without the added TB connectivity (I actually have, as mentioned, the OWC TB4 hub and a 10port USB hub plugged into that, so I have enough ports to not have to plug anything into the monitor), I will just continue with DisplayPort. I have to admit I am still bothered by the need to use a work around, but since it’s easy and effective, so be it.

I suppose there is the possibility of a firmware upgrade to the MBPro or the monitor that will fix a presumed TB incompatibility, ,but I won’t be holding my breath!

Interestingly, when I did have the monitoring working over TB, when I used Displays preference to go to scaled resolutions, I got the box that shows a list of numeric resolutions to choose from, but now that I have it connected over DisplayPort, the default (without option-clicking) is the vertical scroller with 5 pictures of display resolutions. Also weird….

Glad it worked. I am about to try 3 4K LG monitors on the M1 Max MBP. Hope to finally be able to have HDR and nightshift working again, which did not work on the M1 Mini with DisplayLink adapter.

This is a bit upsetting. I had finally decided to go with this monitor mainly because I can only fit 34” in my space and wanted the 5k resolution. The usbc hub and charging was a big sell however, I’m wondering if maybe going for a 1440p 34” ultrawide might be a better choice with a working hub.

It’s certainly a tough call. My use case is that I really wanted a high resolution monitor both because of the sharpness of text as I do a fair amount of writing and reading on screen, and for photography. That was the reason for selecting this monitor. Sadly, the TB issue precludes using the built-in hub aspect, at least as far as a single cable goes.

What I am doing now is connecting via the OWC TB4 hub. I also have TB->Ethernet hooked up to the hub, and I use the USB-3 type A port to connect to an Anker 10port USB hub into which my ScanSnap, external TimeMachine drive, label printer, Benq monitor light, and Logitech webcam are connected. It works, and a single cable connectivity is there with charging from the hub. Since I had bought the hub when it first came out and I had an M1 mini at the time, it’s an easier solution for me than for you as I had already made the hub purchase.

There is one other monitor out there that uses the same panel (at least I assume it’s the same panel as I doubt there are multiple manufacturers for a 34" 5K panel); MSI. That monitor is cheaper, is USB-C and not TB, and so might work where the TB connectivity fails. From the reviews online I got the sense that image quality might not be as good. That always confuses me, but I guess the supporting electronics matter for image quality; it’s not just the panel.

I was also looking at 38" curve monitors, and actually have one on order from ViewSonic. The resolution is lower but I had a chance to order at a significant discount. Shipping is not likely until March, and the other monitors around that seem to use the same panel (LG, Dell) are all backordered so presumably a supply chain issue. The ViewSonic has TB connectivity and an ethernet port which made it attractive, but I will probably cancel the order now that the LG 5K is working over DisplayPort.

Unfortunately, there aren’t a lot of options for a large panel high res monitor and even less if you want reliable performance with Macs, especially with Apple silicon.

Of note: I have read postings online from people who just plugged this monitor in and like magic it worked, no issues. However, I don’t know if they used the TB port or DisplayPort, so I don’t know how to interpret this. It is possible it will work fine for you via TB, but I would suggest making sure you buy from a place that has a low-hassle return policy.

Also, if you are willing to accept two cables instead of one, you can also use the USB-B uplink port to connect to your computer to get the hub capabilities in the monitor. A bit less convenient, and the hassle factor depends on how often you are plugging/unpluggin.

I would note in this overly long response that to use my second monitor (LG 27" 4K) alongside the 5K I have to use two cables because the OWC hub can support 2 x 4K or 1 x 5K, but cannot support a 5K + 4K. I don’t always plug in the 4K and it’s not that big of a deal when I need it. I have not found a hub or dock that can support both a 5K and a 4K over one cable, although I would have guesstimated that 40MB on TB3/4 would have the bandwidth, but perhaps not.

A 38” ultra wide with 1600 dpi vertical resolution is probably the answer for hub with width/resolution/price compromise, but my desk only supports 34” width monitor opening. I ended up ordering 34” ultra wide to try, and if it doesn’t work may go with a single 32” 4k 16:9. The cost of the 5k 27” 16:9 seems a bit exorbitant.

I’ve now had my LG 5K 27" monitor hooked up to my M1 Pro Max for a couple of weeks, and I am very satisfied with the performance. The display is gorgeous and my eyes thank me at the end of every long day in front of it.

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Don’t tell Marco Arment…

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I was unaware that Marco has strong feelings on this…must be behind on my blog reading.

In any case, since I moved the 5K 34” to DisplayPort, I have had no issues and have been very happy with it.

It’s annoying (to say the least) that it did not work over Thunderbolt. I don’t know where the problem lies - with Apple or LG’s TB implementation? - but as I have it hooked into an OWC TB4 hub, I can live without having the downstream USB ports on the monitor anyway.

Ended up ordering both a 1440p 34" ultrawide and a 32" LG ultrafine 4k. The 1440p resolution was not great. The curved screen was cool, but I am not sure that 34" requires curved. I could see 38" needing the curve. I sent it back. I love the 32" LG Ultrafine 4k with ergo stand however. It went on sale at costco for $550 so figured could send it back if I hated it to, but was pleasantly surprised. For my uses the 16:9 4k screen is sharp when 1:1 pixel without scaling, and can make effective use of 4 open windows in the corners. I thought with doing so much documents and spreadsheets ultrawide would have been better, but the vertical real estate lost with 1440p was too much. Also, I am loving the 1 cable usb C life, this in itself is probably worth the cost of admission. I am so happy I didn’t spend the more than double amount on a 5k, I am more than happy with current purchase.


Recently I bought my first 4k monitor below and it works perfectly with a M1 MacBook Pro (Max chip) - plugged in to the HDMI port. (I use a scaled up display setting for my aging eyes. My video needs are just for basic use - not high end graphics…)

Very happy with this purchase.