RX580 + Mac Pro - Dell pixel shift oddity.

Discussion in 'Mac Pro' started by Upgrader, Oct 4, 2018.

  1. Upgrader macrumors 6502

    Upgrader

    Joined:
    Nov 23, 2014
    #1
    Hi

    I've installed my Radeon RX580 Sapphire Pulse into my Mac Pro 4,1 >5,1. I'm on High Sierra 10.13.6.

    I've connected two Dell U1527H monitors via DP out to mini DP in.

    I have a third Apple Cinema display connected via DVI.

    The problem: on the Dell monitors there's a strange pixel shift happening on small text as per the attached picture. This happens on any small text whatever the colour. As you'll see, this isn't happening on the Apple display.

    The pixel shift doesn't happen when I connect one of the Dell displays to my Nvidia GT120.

    I've tried reseating the card. I've tried disconnecting the third Apple display. I've also toggled 'use LCD font smoothing when available' in system prefs which removes the shift on light text on dark but makes the text look awful. None of these things worked.

    Of all the reports I've read about the RX580 install I've not seen this issue. Has anyone else? Does anyone have any insight on what may be causing it?

    Thanks.
     

    Attached Files:

  2. fhturner macrumors 6502

    fhturner

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    Location:
    Birmingham, AL & Atlanta, GA
    #2
    To me, that looks kinda like the aliasing you get when not running an LCD at its native resolution. Can you try changing the resolution around to different settings in System Prefs and see if the behavior changes (or goes away)?
     
  3. Upgrader, Oct 4, 2018
    Last edited: Oct 4, 2018

    Upgrader thread starter macrumors 6502

    Upgrader

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    Nov 23, 2014
    #3
    UPDATE:

    Just tried an HDMI cable and the issue has gone away.

    Not great that the DP ports have issues though. I'll try and test with a better quality DP to DP cable and report back. I should say that I'm using the cables bundled with the Dell monitors.

    --- Post Merged, Oct 4, 2018 ---
    I tried this but any other resolution looks like crap. The Dells are running at native 2560x1440. But to answer the question - no, changing resolutions whilst using the DP to miniDP cable didn't remove the issue.
     
  4. BillyBobBongo macrumors 68020

    BillyBobBongo

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    #4
    This issue arrived in the latest update to High Sierra, I had the same problem. If you upgrade to Mojave, it goes away.
     
  5. Upgrader, Oct 4, 2018
    Last edited: Oct 4, 2018

    Upgrader thread starter macrumors 6502

    Upgrader

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    #5
    Amazing! Thanks so much.

    Strange bug - doesn't happen over HDMI and didn't happen using my Apple GT120 card.
     
  6. IanK MacPro macrumors member

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    Jul 6, 2018
    Location:
    Buckinghamshire, UK
    #6
    I have exactly the same issue with one of my Mac Pros with a RX 580 pulse. Unfortunately due to my 3 MacPro's all being used for work, im not quite ready yet to risk updating to Mojave, plus I need to wait for the NVIDIA drivers on 2 of the machines
     
  7. Upgrader thread starter macrumors 6502

    Upgrader

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    Nov 23, 2014
    #7
    Surprised I've not read of this issue until today as I've been scouring the forums. I might buy a couple of cheap HDMI cables and wait for a few point releases of Mojave before upgrading.
     
  8. IanK MacPro macrumors member

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    Jul 6, 2018
    Location:
    Buckinghamshire, UK
    #8
    yea likewise, maybe its just a RX580+Dell thing? I've just turned off lcd font smoothing for the moment, not ideal but less annoying.
     
  9. Upgrader thread starter macrumors 6502

    Upgrader

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    #9
    I found that turning off font smoothing left small text looking horrible.
     
  10. MarkC426, Oct 4, 2018
    Last edited: Oct 4, 2018

    MarkC426 macrumors 6502a

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    UK
    #10
    I found that on my dell 24 inch looks fine (on dvi), dell 27 inch (dp) pixel shift, but live with it.
    I originally had the 27 connected with hdmi, but found if you had multiple windows open on one display, performance was reduced (a window could only go l/r or u/d, not diagonally).
    With dp not a problem, i think dp supports higher resolutions.
     
  11. Upgrader thread starter macrumors 6502

    Upgrader

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    Nov 23, 2014
    #11
    Really useful info - thanks. Think I’ll give the hdmi cables a miss then. Though do you think this was a software bug? And does the diagonal window thing go away when updating to Mojave?
     
  12. MarkC426 macrumors 6502a

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    #12
    Sounds like it from what bbbongo says.
    Not updated to mojave myself yet.
     
  13. BillyBobBongo macrumors 68020

    BillyBobBongo

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    #13
    There was a thread about 5,1 graphical glitches after updating to 10.13.6 a while back, I sort of hijacked it and talk about this font aliasing issue. It seems to me that's it's purely a software thing as issues started appearing after I updated to 10.13.6.

    I'm on Mojave these days, my RX 580 is connected via DisplayPort, and I no longer have these issues.
     
  14. h9826790 macrumors G5

    h9826790

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    Hong Kong
    #14
    I force the UI to render at HiDPI to "fix" this issue. And it's nothing about RX580. Same thing happen on my 1080Ti. So, it's definitely how the OS designed to render the text (under that particular condition).

    As you can see in the comparison. For the same monitor, same size, The forced HiDPI one produce much clearer text.
    HiDPI Comparason.jpg

    Even the front smoothing is better in Mojave. But still not as clear as Forced HiDPI rendering, and then scale back down to the native resolution. This is actually the same concept as High Dynamic Resolution in gaming.

    Anyway, this is how I do it.

    https://forums.macrumors.com/thread...mac-edition-card.2101909/page-7#post-26618588
     
  15. Upgrader thread starter macrumors 6502

    Upgrader

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    #15
    Thanks - I'm going to try this.
     
  16. stiwi macrumors regular

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    Singapore
    #16
    I have exactly the same issue. Thing is I have 2x Dell monitors and after switching from HDMI cable to DP, I thought maybe I am tired or something, just to stumble upon this post! This issue was not present via HDMI, which is strange as it is less natively supported format by Apple in general. I am also on 10.13.6, about to upgrade to Mojave right now, to hopefully resolve this strange issue...
     
  17. Upgrader thread starter macrumors 6502

    Upgrader

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    #17
    I found that testing with an HDMI cable solved the issue too on High Sierra. I've just upgraded to Mojave and the issue has now gone altogether.
     
  18. stiwi macrumors regular

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    Singapore
    #18
    Same here.
     
  19. Upgrader thread starter macrumors 6502

    Upgrader

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    Nov 23, 2014
    #19
    --- Post Merged, Oct 7, 2018 ---
    Happy to confirm that I’m also now on Mojave and that the pixel shift has now ceased. Happy days.
     

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18 October 4, 2018