Faint vertical lines/static on external display connected to M1 MacBook Pro

I was experiencing the same issues with my LG Monitorys. I had to disable freesync as it was interfering with the hdmi signal.

I have only experienced this on the m1(m1 pro 14) and not my other intel variant.

Double check your monitor settings for Freesyn/Gsync and disable. Hope this helps

A brief update: I managed to partially solve the problem by changing the color profile of my external display. After testing different profiles, I noticed that the default profile for my display does not present the lines when the image is static. If the background is moving, you can briefly see the lines, but they disappear shortly after. It's actually very hard to notice, but it's there. Either way, it's way better than how it was before.

I, too, was having this issue until I came to this thread and started monkeying around with things.

System: MacBook Pro M1 16G Ram, 1TB NVMe

Monitor: 1080p Viewsonic

Locale: USA (keep reading to see why this might matter)

What I found: This monitor, for some reason, wants to default to running at 50Hz rather than 60Hz. I have switched it to run at 60 HZ to reduce the flicker. After visiting this thread I wondered if switching it to 50 HZ would help. The problem went away. More interestingly though, when I switched it back to 60 Hz the problem has not come back. At least not yet.

This is obviously anecdotal at best but it can't hurt to give this a try and see if it helps.

HDMI “high speed” will probably work here, though the whole thing is as much of a mess as USB-C.

Tried the other HDMI port?

The 2311 series has a few different HDMI modes, see if there’s a way to view what’s been selected:

Page 29 shows the HDMI modes http://h10032.www1.hp.com/ctg/Manual/c03351672.pdf

It looks like the 2311 series has an on-screen display that might allow selecting those different modes.

I’d guess there’s a marginal display mode on the HP display, but that’s a guess.

I have just got my Dell 34'' curved monitor today and I found this fixes it, but only temporarily.

System Preferences --> Displays --> Have the settings that you want for your external monitor, then go to Arrangement tab --> Check if the Mirror Displays box is ticked or unticked. For me I want this box to be unticked so if it's 1) ticked, I will untick, tick and then untick again 2) unticked, i will tick and untick.

I found this helps with this problem, but it is very inconvenient because I lock my screen every time when I go to toilet or do something or leave my table and every time when I lock back in, the problem will always come back and I need to repeat those steps every time. I am not very good at tech so please either Dell or Apple, fixes this.

I’m wondering if the M1 is selecting a here-less-than-compatible resolution configuration, while the others are selecting a more compatible one.

Which of the various HP Pavilion monitor models is that one?

Which HDMI spec does the monitor it support?

Is the cable capable of the monitor connection?

HDMI cables are differentiated by bandwidth, and older cables are older spec.

HDMI deliberately made this determination difficult, unfortunately.

The cables you want for HDMI-only Monitors (higher resolutions than 720p TV sets) are marked as Certified with an anti-counterfeiting tag and are labeled:

"Premium High Speed HDMI cable" or that + "with Ethernet"  --OR--

"Ultra High Speed HDMI cable" or that + "48G"

Cables with No Certification tags are good for your standard TV set, and not much more.

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If at all possible, try to use DisplayPort family cabling, or its equivalent over thunderbolt or USB-C.

Hi! I'm also having this exact problem with my base model MacBook Air M1, connected to a 23" LG monitor (23MP55, 1920x1080@60Hz) using a HDMI cable and an Anker USB-C Hub.

The lines are mainly visible when a darker background is present, and are usually around the center of the screen. If I move the window around the screen, the lines disappear. I tried changing cables but it didn't help. I don't have another USB-C-to-HDMI adapter to test.

I've been using this monitor for years now, and I've never had a problem before. Can it be a software issue, since others are experiencing this too?

Yeah, unfortunately the M1 doesn't like every monitor. I went to the Apple store about this exact same issue and they told me that it might be fixed in a future update but it seems to be a gpu issue. When i went to the apple store they connected it to cheap monitor and it didn't do this at all. I am using a cheaper 1080p monitor and it does this and it bothers me so much just feels cheap to me.

I also am having this problem on my MacBook Pro M1 13-inch running 11.4. The issue happens on two separate monitors tried independently and at seemingly random times. I have tried different cables and it seems to happen no matter what. I have tried multiple DisplayPort cables, Mini DisplayPort to type c, an hdmi cable with a type c adapter. All eventually have the issue.

I have noticed that the lines, once they show up, actually sometimes stick around on my monitors even after disconnecting the signal from the MacBook. If I launch the monitors OSD, I can still see them. They only go away after leaving the monitor off for a while or running the LCD conditioning in the OSD.

I have tried varying refresh rates from 50hz all the way up to 240hz and the problem eventually happens no matter what. I have also disabled auto brightness and True Tone just to test and neither seemed to make a difference. I also forced the MacBook M1 to output in RGB instead of YCBCR by editing a .plist file but that also made no difference.

I have tested both of these monitors at length on my two PC’s as well as on my old Intel Mac and the monitors are totally fine. This issues is 100% caused by the MacBook M1.

If anyone else has any ideas, I’m all ears as I am at my wits end here and might just return this MacBook. It is hindering my daily work at this point.

My monitors are:

Alienware 2521HF

Alienware 2721D

That is pretty much exactly what I am seeing. And i do think you are correct, it is something about the monitor with what I assumed was the new graphics chipset on the M1. From reading reports, the issue seems to happen on only certain monitors but on a large scale. Like certain Dell monitors seem to have issues across the board. Both my Dell and my Alienware experience the issue when hooked up to my M1 but they work fine when used with my older Intel based Macbook Pro. I think something about the new Mac graphics chipset triggers something or corrupts a part of the monitor signal because once the problem occurs for me, the lines will often stay on the monitor even after I unplug my displayport or HDMI cable or after power cycling. The only thing that seems to help is messing with the refresh rate to make the lines go away or unplugging everything from the monitor and letting it run its LCD conditioning function for a couple minutes. It's really a crazy problem and I can't believe there hasn't been some kind of official response about it. Even if Apple were to release a list of possible monitors that are known to be problematic. I mean, I'm at the point where I just don't hook an external monitor up to my Mac and I have just been using my old one for work stuff.

You have 14 days from receipt to return Apple products purchased direct from Apple for a full-value refund or exchange.

(Must be in the same country as purchased, and not available in some countries in the Far East, including Hong Kong and Singapore, and possibly others)

Same problem here: I have a Mac Mini M1 - 16GB (Big Sur 11.4) and a DELL P2721Q (4K / 60Hz) display. Here are some findings:

• Using HDMI or USB-C makes no difference
• The problem (vertical lines & flickering) happens randomly at different times of the day and disappears after 10 minutes automatically, or after rebooting the system
• I'm facing the issue about 1-2 times a day
• If I connect my old Macbook Pro 2015 with Thunderbolt to the display I have no issues
• CPU usage seems to have an impact on the problem, eg. if I use a crazy synth-effect in Logic Pro the flickering is more intense than without
• I'm also using Dark Mode, haven't tried Light Mode yet (Because Light Mode is no option...)

Hope this helps.

Grant is correct: this is a hardware issue pertaining to the display itself. On my display, the issue is intermittent; the lines usually appear when I first wake my computer up, and then they gradually either fade or just disappear altogether. They seem to vary in intensity — occasionally, being so severely apparent that they're an utter distraction for me.

All you and I need is for someone familiar with displays to identify the potential cause. From what I know, it could be either the T-*** board or the LCD panel. (It could even be the cables themselves, which lead to the T-*** board.) I'm getting close to just biting the bullet and ordering a replacement T-*** board for my Apple Cinema Display 30", since a used one is only $15-25. However, if a replacement board has no effect, I'll be sorely disappointed by the wasted effort. I'd cut my losses now, but I just otherwise love this display.

Does it seem to happen to you more if you lower your refresh rate? On my Alienware AW2521HF, if I set it to 240hz, it seems to take a while longer for the issue to crop up.