0

I have 2 LG 27GP950-B (4K) external displays, which I connect to MacBook via USB-C->HDMI and HDMI->HDMI cables. Prior to using these with the MacBook, I was using these with a desktop PC for a year with no problems. Hence I think the MacBook is involved.

Every now and then (2 times in 2 weeks now), seemingly out of nowhere the strangest things happen. One of my external displays (happened to both of them now) starts to act weirdly: the colors change and vary greatly if I move the windows around on that display (looks like some scrambled video signal), the backlight starts to flicker, but worst of all it seems like a CRT burn-in, or stuck pixels. I can literally see another window's contents through another non-transparent window. The burn-in is very real: even with no signal, the image that was on the display is perfectly readable. I'm anxious it's going to permanently damage my displays.

I tried turning off all the automation I could find for the built-in display, like True Tone, Auto Brightness etc; set the Color Profile for the external displays to generic Color LCD, change the scaling from ~150% to 200%. It didn't help. The refresh rate is at 60Hz.

  • Do you think it has potential to permanently damage my displays? (The previous one has recovered in a few hours)
  • Does it really sound like stuck pixels?
  • Do you have any potential solutions?
13
  • 1
    The Mac simply cannot send a signal that will damage your monitor. It’s just 0s and 1s. How the LED panel handles that data is what gets output. If you’re seeing ghost images with no HDMI connection, the issue is the monitor
    – Allan
    Mar 21, 2023 at 18:10
  • 1
    So if you took a screen shot of the Mac display and played that from the PC - that has to have the same persistence / burn in - other factors like age / brightness / screen saver would be where I'd focus my attention.
    – bmike
    Mar 21, 2023 at 19:02
  • 1
    I have the same problem. Monitor works fine at 144Hz from a Windows PC, but from an M2 it creates vertical lines and burn in at 144Hz at certain colours (grey). This is via DisplayPort. Monitor is an Alienware 38 AW3821DW.
    – gak
    Jul 14, 2023 at 19:23
  • 1
    @PavelGurkov I'll be following this question on AD. If I find a solution I'll make sure to post the answer here. I'm afraid it's damaging my monitor.
    – gak
    Jul 14, 2023 at 19:26
  • 1
    @PavelGurkov Nothing has worked so far. I didnt go down to 30Hz because I might as well not do any work. It's way to janky for me. I did painfully try 60Hz for a while and the same problem happened: flickering screen/burn-in. The inbuilt display frequency didn't make a difference. I'm not sure why it would make a difference anyway.
    – gak
    Jul 24, 2023 at 3:08

1 Answer 1

1

Well, I've found that I'm not the only one with this issue, and this issue is indeed specific to M1 Macs. Check this link for discussion: https://forums.macrumors.com/threads/macbook-pro-m1-external-screen-flickering.2325279/

I've found that either of these workarounds achieve no flickering, no weird colors, no still burnt-in images:

  • Lower the refresh frequency of the external displays to 30 Hz
  • Lower the refresh frequency of the built-in display from "ProMotion" to 60 Hz
6
  • 1
    Correlation ≠ Causation. Time is a key factor for screen burn in or Image Persistence. A GPU simply cannot send a signal to a display that will cause this. It is much more likely that the LG panel (which have had their own slew of video issues) is not handling the refresh rates that the GPU delivers. The fact that you had to change the refresh on the internal display to make an external display work is indicative of a problem with the external display; the Mac works fine. I’m not finding this issue with Dell, Sony or Planar monitors.
    – Allan
    Mar 25, 2023 at 17:44
  • 1
    Maybe you're lucky. Maybe I'm unlucky. Maybe the temporary screen burn-in is a combination of factors here. It never happened before even if the display would stay on for 12 hours with the same image. If you check the thread I linked, there are people reporting the flicker with Dell monitors. The displays I'm using work fine on 144Hz, and on 60Hz with Mac with aforementioned changes, and on 30Hz. To be honest, I don't see any connection between my workarounds and the fact they work, but they do and it's good enough for me. Mar 26, 2023 at 15:01
  • Temp. Burn in can only be a factor of the display panel, not the source. I don’t put much stock in “people reporting” because too often there is a rush to unsubstantiated conclusions. I”m not saying the Apple GPU is perfect, rather it simply cannot cause the symptoms you describe or the solution/workaround pointing to a fault with the GPU and not the display.
    – Allan
    Mar 26, 2023 at 15:18
  • 1
    @Allan so confident. I would have said the same thing as you, but yet, it’s happening to me as well with a high-end Dell design monitor. I’ve had a 2012 MacBook Pro, a 2018 MacBook Pro, and 4 different PCs attached with no issues. Hook up a 2022 MacBook Pro M1 and it ghosts like a mofo—only takes a couple minutes of an iTerm window sitting there and I can literally read the contents still when I move the window away. There has to be something going on with the Apple signal, or color profile or… who knows.
    – mpowered
    May 4, 2023 at 6:00
  • 1
    @mpowered thanks for confirming I'm not going insane! May 4, 2023 at 16:32

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .