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LG UltraFine 5K - Owners Thread
- Thread starter iBrooker
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Thanks for getting back. I've now tried with another laptop - running an older OS - and the colour cast remains. Searching the net it seems that some kind of LG motherboard failure can produce this result. Must have coincidentally happened at the same time (as OSX26). May have to go in for service. Annoying this happens when there's rumour that an upgraded Apple Studio is imminent.
Try unplugging the Mac entirely (both the Thunderbolt and mains cables). Leave it off for 15 minutes or until the display is completely cold. Plug the Mac back into the mains and ensure that the power supply you’re using can provide the maximum wattage the machine accepts (e.g., don’t use a 30W power supply on a 60W device—you want to make sure no USB-PD connection is established with the display). Turn on the display using AC power. Wait for 30 seconds. Plug the Thunderbolt cable into the display first, and then the Mac. Repeat this process five times. If you get the same result every time, the logic board on the display is likely faulty. If the color cast disappears, the device fails to connect, or you notice any strange intermittent issues (e.g., USB or audio connection established but no display) during one of those five connection attempts, it’s most likely that the pads or traces around the Thunderbolt port have degraded. This degradation causes strange intermittent issues due to thermal expansion and contraction.
I own numerous of these displays, and the troubleshooting process is consistently frustrating. The only solution is to persistently attempt various combinations of plugging and unplugging. If the results remain consistent, the issue lies with the logic board. Conversely, if the results are intermittent, it’s almost always the pads on the connector itself. At least this has been my maddening experience with these displays.
I wish I could find a second one for sale locally at a decent price. Mine is still going strong since new in 2021, though I have never connected anything to the inbuilt USB-C ports. After reading about the thermal issue here, I never will! 
The USB-C ports are safe to use and likely will not fail. The issue is the single Thunderbolt port—that is the one that fails.I wish I could find a second one for sale locally at a decent price. Mine is still going strong since new in 2021, though I have never connected anything to the inbuilt USB-C ports. After reading about the thermal issue here, I never will!
Thanks. I should have been more specific regarding your caution using PD. I use a CalDigit for all of my USB-C data and PD needs.
Thanks for this. Tried the lengthy voodoo like sequence of manoevres 3X (not 5)... I guess it's a logic board fault.
FWIW don't ever plug/unplug the cable from the monitor so my connector has a good chance of being in reasonable shape.
I bought an 27MD5K for $300 + $100 shipping. It arrived the next day, and it ended up being a 27MD5KA model. I was a little disappointed but I guess what can you expect? I was hoping for a newer model with less issues and the iPad Pro support like my other one. But the owner who bought it, said it works great and he upgraded to a dual Studio Display.
Anecdotally at least, is this issue ONLY with Thunderbolt Power Delivery to laptops? What about with Mac minis, Mac Studios, and Mac Pros?
I just ordered the LG UltraFine 6K 31.5" model, and haven't decided yet if I'm using Thunderbolt or HDMI. My M4 Mac mini has HDMI 2.1 so I have both options available to me. I'm leaning toward HDMI 2.1 though since it'd be nice to free up a Thunderbolt port, the M4 Mac mini doesn't support Thunderbolt 5, and I don't have any Thunderbolt 5 devices anyway.
I have never had an issue with my M2 Pro Mac mini before or my M4 Pro Mac mini now.... The thunderbolt area does NOT feel warm at all. Probably because the Mac mini like the other Mac desktops are display only and have their own external Power. While the MacBooks do both display and power thru the Thunderbolt port.
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Primarly yes, but the display can fail even without PD. It's just very poorly designed.
No one knows about the new model. Hopefully they have fixed the issues with the old design… it's certainly been long enough.
I am on the latest MacOS and idiotically decided to check to see if there are any firmware updates for my monitor...
There were, so I used LG Screen Manager to update it and every time it fails at 20%, seems like it does nothing, and then my monitor goes black some random amount of time later and needs a full on power disconnect to boot back up again. It goes black shortly after.
Is there any secret to getting the LG Screen Manager to not crash out at 20%? I looked for permissions or security blocks but didn't find any.
There were, so I used LG Screen Manager to update it and every time it fails at 20%, seems like it does nothing, and then my monitor goes black some random amount of time later and needs a full on power disconnect to boot back up again. It goes black shortly after.
Is there any secret to getting the LG Screen Manager to not crash out at 20%? I looked for permissions or security blocks but didn't find any.
So, you're on Tahoe, with an Apple Silicon Mac? I had the exact same problem with my M4 Mac mini with Tahoe 26.1, trying to update the firmware on my LG UltraFine 6K. Every time around 20-50% complete, the disk image with the firmware that the application opened would dismount, disrupting the upload of that firmware to the monitor. I tried this multiple times, including after a couple of reboots of both the monitor and the Mac. It failed every time.
Finally I gave up and then tried my 2017 12" m3 MacBook on Ventura, and that worked the very first time.
Hi there, I just purchased a used 27MD5KL-B (production date May 2022) to pair with my M1 Max MBP. It looks fantastic and appears in great condition overall but I had a few questions I’m hoping the community can help with:
- Reading the thread, it appears the big issue with these monitors is the thunderbolt port getting cooked over time. Am I right in understanding that this issue is preventable if you use a powered TB dock between the laptop and the monitor? I’m considering a used Caldigit TS3 Plus as an option but is there an easier solution? Eg. Just plugging in the Macbook charger? The TB connection currently works flawlessly and doesn’t feel particularly warm to touch on the back of the monitor so I’m keen to keep it that way if I can.
- Do these powered TB docks all generally deliver full 5K resolution? I’m only using one external display, with the MBP serving as my second display. Any advice on affordable (or used) makes or models to look out for would be appreciated. Ideally looking for something with a small footprint to preserve desk space.
- Finally, there is very minor pink tint on the lower corners of the screen but it’s barely perceptible even on a white screen. I thought I read somewhere that this can be calibrated out. Can anyone confirm? I also read this can get worse over time… How quickly can the issue intensify?
Thanks all
- MBP will use more powerful charger, so if it provides more than 94W, it will be chosen as power source. You can check which power source is used in System Information > Hardware > Power (AC Charger Information) or with iStat Menus:
But both power sources should be connected before powering up. It may not switch to your AC adapter if you connect it later.
- Yes, they do. I bought a used cheap Lenovo TB3 Dock and works flawlessly. High-quality TB3 cables are required.