Display lines on 27-inch iMac may be Radeon Pro 5700XT GPU issue

Posted:
in Current Mac Hardware edited August 2020
A very small number of 27-inch iMac users are reporting issues with their Mac's graphics, with some encountering random screen glitches in the form of lines appearing on the display.

An example of the graphical glitch [via Apple Support user Bunn_pt]
An example of the graphical glitch [via Apple Support user Bunn_pt]


In a post to Apple's Support Forums, users have documented the appearance of small lines on the screen of current-generation 27-inch iMacs. Images and video from one user reveal the glitches as being a single white line that spans the entire width of the desktop, one that briefly appears at seemingly random times.

According to the user, the glitch is "completely random" in its appearance, as it doesn't seem to manifest just during intense workloads, and even appears when the Mac is idle. The post from August 26 reveals the issue was affecting an iMac with a 3.6GHz 10-core Core i9 processor, 32GB of memory, and AMD Radeon Pro 5700 XT 16GB graphics.





Other users claim to have determined the source of the issue may be the 5700XT GPU that ships with the model, though was still waiting for Apple's support team to get back in touch about the problem. One person claims Apple Support advised to reset the SMC and NVRAM as a fix, which seemed to solve the problem for that particular user.

Another noted an identical issue, but added that it didn't seem to appear while using Windows 10 on the Mac. The user speculated it was a GPU driver issue.

The issue appears to affect a very small number of users. Public reporting of the issue isn't widespread, suggesting it doesn't affect all users of an iMac equipped with that particular GPU.

AppleInsider is not able to reproduce the issue on two different iMacs with the upgraded GPU. Additionally, zero of the service locations we have spoken to on other matters have seen the issue.

Even though the issue appears to be related to the macOS drivers for the GPU, we still recommend documenting the case with Apple, if you are experiencing the issue.
RootlessCosmopolitan

Comments

  • Reply 1 of 10
    I have experienced graphical glitches consisting of triangles and lines on my 2020 iMac w. 5700XT. It requires a reboot to resolve them. I am also experiencing crashes where the whole system becomes unresponsive also requiring a (hard) reboot. I can replicate this consistently by playing Civ 6 - it typically freezes 20 minutes into a session.
    Indoor_AstronautRootlessCosmopolitanwatto_cobra
  • Reply 2 of 10
    dysamoriadysamoria Posts: 3,430member
    cdoubleu said:
    I have experienced graphical glitches consisting of triangles and lines on my 2020 iMac w. 5700XT. It requires a reboot to resolve them. I am also experiencing crashes where the whole system becomes unresponsive also requiring a (hard) reboot. I can replicate this consistently by playing Civ 6 - it typically freezes 20 minutes into a session.
    Yet another GPU thermals issue?
    sunman42RootlessCosmopolitanelijahg
  • Reply 3 of 10
    cdoubleu said:
    I have experienced graphical glitches consisting of triangles and lines on my 2020 iMac w. 5700XT. It requires a reboot to resolve them. I am also experiencing crashes where the whole system becomes unresponsive also requiring a (hard) reboot. I can replicate this consistently by playing Civ 6 - it typically freezes 20 minutes into a session.
    What you describe is verbatim what has been happening to me. The only difference is I'm running the 5700 and not the 5700XT everyone else seems to be having issues with. Apple Support had me run through all the usual steps to fix it but no resolution. I'm really questioning if this is a driver issue or faulty hardware/design.

    elijahgwatto_cobra
  • Reply 4 of 10
    sunman42sunman42 Posts: 195member
    dysamoria said:
    cdoubleu said:
    I have experienced graphical glitches consisting of triangles and lines on my 2020 iMac w. 5700XT. It requires a reboot to resolve them. I am also experiencing crashes where the whole system becomes unresponsive also requiring a (hard) reboot. I can replicate this consistently by playing Civ 6 - it typically freezes 20 minutes into a session.
    Yet another GPU thermals issue?
    Would you be willing to tell us how much graphics memory you got with the 5700XT (8 or 16 GByte)? Thanks.
    watto_cobra
  • Reply 5 of 10
    sunman42sunman42 Posts: 195member

    cdoubleu said:
    I have experienced graphical glitches consisting of triangles and lines on my 2020 iMac w. 5700XT. It requires a reboot to resolve them. I am also experiencing crashes where the whole system becomes unresponsive also requiring a (hard) reboot. I can replicate this consistently by playing Civ 6 - it typically freezes 20 minutes into a session.
    Would you be willing to tell us how much graphics memory you got with the 5700XT (8 or 16 GByte)? Thanks
    watto_cobra
  • Reply 6 of 10
    sflocalsflocal Posts: 6,017member
    dysamoria said:
    cdoubleu said:
    I have experienced graphical glitches consisting of triangles and lines on my 2020 iMac w. 5700XT. It requires a reboot to resolve them. I am also experiencing crashes where the whole system becomes unresponsive also requiring a (hard) reboot. I can replicate this consistently by playing Civ 6 - it typically freezes 20 minutes into a session.
    Yet another GPU thermals issue?
    There is nothing yet to imply what the "issue" is.  The video shows nothing more than a Twitter page running.  So thermals can't be much.  There's a myriad of things it could be, but of course everyone has to start with conspiracy theories.
    watto_cobra
  • Reply 7 of 10
    cdoubleu said:
    I have experienced graphical glitches consisting of triangles and lines on my 2020 iMac w. 5700XT. It requires a reboot to resolve them. I am also experiencing crashes where the whole system becomes unresponsive also requiring a (hard) reboot. I can replicate this consistently by playing Civ 6 - it typically freezes 20 minutes into a session.
    I have been experiencing exactly the same issue, i.e., playing Civ 6 on my new 2020 iMac w/ 5700 xt causes the iMac to crash. The screen looks the same, too, with graphical glitches that look like shards. 

    I reset SMC & NVRAM but the problem persists. 

    My 2020 iMac: 
    ・2020 27-inch iMac
    ・3.6 GHz 10-core Intel Core i9
    ・32 GB RAM
    ・AMD Radeon Pro 5700 XT 16 GB
    watto_cobra
  • Reply 8 of 10
    just a guess; maybe the 5700xt does not function has it should with games in 10-bit HDR display mode like it does with movies or images. 
    edited August 2020 watto_cobra
  • Reply 9 of 10
    Joer293Joer293 Posts: 29unconfirmed, member
    I haven’t played games, but the line glitches appear, under idle conditions. 27” 10core i9, 128gb and 16gb 5700xt. I have not seen the tearing others have.
    on pc’s I’ve owned this was a spread spectrum/clocking/voltage fix. No idea how to test that on an iMac. 
    watto_cobra
  • Reply 10 of 10
    cdoubleu said:
    I have experienced graphical glitches consisting of triangles and lines on my 2020 iMac w. 5700XT. It requires a reboot to resolve them. I am also experiencing crashes where the whole system becomes unresponsive also requiring a (hard) reboot. I can replicate this consistently by playing Civ 6 - it typically freezes 20 minutes into a session.
    maybe these helps to troubleshoot a bit! https://www.techpowerup.com/forums/threads/rx-5700-xt-75-hz-144-hz-non-standard-refresh-rates-causing-vram-clock-to-run-at-max.260806/
    watto_cobra
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