Same issue here with the same monitor, but I'm using a M1 MacBook Air. Doesn't do it all the time, but just did it twice in the past hour. Once for about 15 seconds, this last one for about 2-3. So odd.
Got a tip for us?
Let us know
Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
Intermittent monitor blank outs on LG UltraFine 4K with Mac mini M1
- Thread starter mackiee
- Start date
- Sort by reaction score
Mac mini m1 running view sonic 34” widescreen same blanking issue. Sent back to Apple logic board replaced. Upon return it’s having the same problem. Zero software or peripherals installed. Blanks out when sitting idle. Issue on both usb-c and hdmi. Monitor works fine on other machine. Cables are all good.
Sadly, I'm now on 11.3 beta and still getting the issue of the monitor not coming back from wake. Whether it's hardware or software related, clearly Apple has not been able to fix it. Pretty disappointing.
M1 MBA on 11.3, display issues seems to be resolved.
Been able to connect the M1 to a 1440p@144hz 27" display and Sidecar at the same time.
The display outputs at 100/120/144hz only when connected to the right Thunderbolt port.
Using a no-brand 4k@60 TB3 adapter and HDMI 2.0 cable.
On the left TB port the display remains off when choosing any refresh rate option above 60hz when at any resolution.
The connection is stable when first connecting the external display and setting the desired refresh rate then enabling sidecar.
Zero issues with sleep wake
Been able to connect the M1 to a 1440p@144hz 27" display and Sidecar at the same time.
The display outputs at 100/120/144hz only when connected to the right Thunderbolt port.
Using a no-brand 4k@60 TB3 adapter and HDMI 2.0 cable.
On the left TB port the display remains off when choosing any refresh rate option above 60hz when at any resolution.
The connection is stable when first connecting the external display and setting the desired refresh rate then enabling sidecar.
Zero issues with sleep wake
Last edited:
I bought a refurbished Mac mini mi with 16GB/1TB configuration about 3 weeks ago. I am using it with a Dell ultra sharp 4K monitor through hdmi and Logitech Bluetooth keyboard and mouse. The first couple of weeks I did not have any problems. Then starting this week, the monitor blanks out for a second and comes back. I also noticed my mouse goes unresponsive for a few seconds and then comes back. Yikes.
I also have this intermittent problem with a Mac mini 16/2 connected via USB-C to a Dell U3421WE monitor.
The monitor has built-in speakers, and when it's "asleep" (it's not really asleep, the screen is black but you can see the backlight is on), when I awaken it the monitor will beep about 2 times/second. Drives me insane. Contacted Dell and they are replacing the monitor, but I have a feeling that is not going to fix it.
The monitor has built-in speakers, and when it's "asleep" (it's not really asleep, the screen is black but you can see the backlight is on), when I awaken it the monitor will beep about 2 times/second. Drives me insane. Contacted Dell and they are replacing the monitor, but I have a feeling that is not going to fix it.
Considering my 2017 iMac does this on its built-in display, I really wonder if it is related to this thread at all or just the one thing they all have in common: Big Sur.
Please call Apple and get through to a real tech support analyst to log this complaint. I've had the same issue with my iPad Pro, where it won't display the iPad display, but will charge and play sound. It's not the iPad.
The official LG Screen Manager app on the Mac App Store is incompatible with M1 Macs as well - so you can't even upgrade the firmware via the macOS app.
The issue gets "upvoted" in a sense if more people call and mention issues. The iPad one is quite egregious b/c the iPad is listed as compatible with the LG monitor and it clearly is not at the moment.
The official LG Screen Manager app on the Mac App Store is incompatible with M1 Macs as well - so you can't even upgrade the firmware via the macOS app.
The issue gets "upvoted" in a sense if more people call and mention issues. The iPad one is quite egregious b/c the iPad is listed as compatible with the LG monitor and it clearly is not at the moment.
I have the same random blackouts on my LG 32UL750. The monitor was purchased new just 6 weeks ago. Connected to MacBook Pro (13-inch, M1, 2020) with supplied Thunderbolt cable. Triggered by nothing in particular. Just working with text and images.
Well I've had my MacMini for some time now. I get blackouts on one of my two Dell monitors at least once a week from sleep. A restart from the menu usually fixes it, but today I had to do a hard re-boot with the M1 MacMini power button. Sigh.
M1 Mini here, with bog-standard Dell and AOC 32" (2560x1440) monitors. The Dell was HDMI-to-HDMI, the AOC was HDMI-to-USB/TB. After eight months of working perfectly well, the AOC started blacking out for a few seconds, maybe once or twice an hour. Changing cables or using a dongle had no effect, nor did shutting down and rebooting the Mini.
I swapped the output cables (AOC on HDMI, Dell on USB/TB) and now it's the Dell that blacks out. I moved the cable to the Mini's other USB/TB port, and the problem remains. So the issue is with the USB/TB video signal - i.e., a fault within the Mac itself.
I'll talk to Apple about a replacement, since I'm still under the original warranty. This is my work machine, so I hope it's a quick swap, and not a ship-it-to-Apple-and-wait-indefinitely situation.
I swapped the output cables (AOC on HDMI, Dell on USB/TB) and now it's the Dell that blacks out. I moved the cable to the Mini's other USB/TB port, and the problem remains. So the issue is with the USB/TB video signal - i.e., a fault within the Mac itself.
I'll talk to Apple about a replacement, since I'm still under the original warranty. This is my work machine, so I hope it's a quick swap, and not a ship-it-to-Apple-and-wait-indefinitely situation.
I bought a refurbished M1 Mac mini that has had this problem from the beginning. Apple support asked me to upgrade my OS, etc. I also had a Bluetooth issue where every few minutes my Logitech Bluetooth mouse would stop working and then it would work again. That problem seems to have resolved itself somehow. My mini is my personal machine and I use the hdmi from my dell 4k monitor. May be I can change it to thunderbolt and see if that makes it worse. I have the problem through hdmi and thunderbolt.
Update on my M1 Mini: Took it to an authorized Apple shop, where it passed every diagnostic test they were able to run on it. Blackouts were noted using their cable and their monitor. A new logic board is now on order.
Seems to be a hardware issue, but I'm fortunately still under warranty.
Seems to be a hardware issue, but I'm fortunately still under warranty.
Last edited:
Update to the update: Apple auth. repair shop replaced the logic board in the M1 Mini. They ran it for a day, saw no problems, and I took it home - where the problem resumed within half an hour. 
Again it's only the monitor on the USB-C port that's blacking out. Mac OS Monterey (12.2) gives me a choice of 75 or 60 Hz refresh rates, neither of which solves the problem.
They were attaching 24" monitors at the shop, while I have 32" screens. Maybe this is limited to larger monitors - is anybody having an issue with a smaller external screen?
Again it's only the monitor on the USB-C port that's blacking out. Mac OS Monterey (12.2) gives me a choice of 75 or 60 Hz refresh rates, neither of which solves the problem.
They were attaching 24" monitors at the shop, while I have 32" screens. Maybe this is limited to larger monitors - is anybody having an issue with a smaller external screen?
To whom it may concern.
I recently bought a 2020 Mac Mini M1 and had the same problem with my LG 4K UHD Monitor (Model: 27UL500). I was using a nice (or so I thought) HDMI cable to plug it into my monitor. Since the issue began I tried messing with settings and what not, to no avail. I even put a call in with Apple Support and the guy was perplexed. The only strange thing was that the mac detects my monitor's resolution (in the "System Report" under "Graphics/Display") as "5120 x 2880 (5K/UHD+ - Ultra High Definition Plus)", when in fact my actual native resolution is "3840 x 2160", so I thought this must be a hardware bug on the Mac Mini M1.
That said I went and grabbed my 4K TV's (also an LG) nicer HDMI cable, which was marketed as being able to support up to 8K resolution and I haven't had the problem since. It has only been a day or so on the new cable but so far no blanking out issues. Also, it appears only the Mac Mini M1 has a problem with the first HDMI cable. My Lenovo Laptop, PS5, and 2016 MacBook Pro don't have this issue.
Just wanted to post this here in case it might help someone. Good luck!
I recently bought a 2020 Mac Mini M1 and had the same problem with my LG 4K UHD Monitor (Model: 27UL500). I was using a nice (or so I thought) HDMI cable to plug it into my monitor. Since the issue began I tried messing with settings and what not, to no avail. I even put a call in with Apple Support and the guy was perplexed. The only strange thing was that the mac detects my monitor's resolution (in the "System Report" under "Graphics/Display") as "5120 x 2880 (5K/UHD+ - Ultra High Definition Plus)", when in fact my actual native resolution is "3840 x 2160", so I thought this must be a hardware bug on the Mac Mini M1.
That said I went and grabbed my 4K TV's (also an LG) nicer HDMI cable, which was marketed as being able to support up to 8K resolution and I haven't had the problem since. It has only been a day or so on the new cable but so far no blanking out issues. Also, it appears only the Mac Mini M1 has a problem with the first HDMI cable. My Lenovo Laptop, PS5, and 2016 MacBook Pro don't have this issue.
Just wanted to post this here in case it might help someone. Good luck!
Apple Mac mini, M1 Chip 8-Core CPU, 8 GB RAM, 1 TB SSD, 2020
from March 2021
one LG 32ul750-w via USB-C
one LG 27 UN38A via HDMI
I have noticed this problem since the beginning. I have sent one display back to the supplier. Have tried different cables. No change.
from March 2021
one LG 32ul750-w via USB-C
one LG 27 UN38A via HDMI
I have noticed this problem since the beginning. I have sent one display back to the supplier. Have tried different cables. No change.