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MP 1,1-5,1 Mac Pro 5,1 RX580 – Dual HDMI Displays Limited to 30 Hz After Monterey Upgrade (No Hardware Acceleration?)

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macrumors newbie
Original poster
Oct 31, 2025
4
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Hi all — I’ve searched, but haven’t quite found my exact situation. Apologies if this has come up before.


I’ve got a mid-2012 Mac Pro 5,1 (dual 3.46 GHz Xeons, 96 GB RAM) with an RX 580 GPU.
I’ve been running Mojave very successfully for a couple of years — triple-monitor setup, plus a PCIe audio card for my Pro Tools rig.


Recently I upgraded to macOS Monterey 12.7.4 using OpenCore Legacy Patcher to keep things current for web apps and other compatibility reasons.


Everything runs and boots fine, and all three displays work — but I’m seeing serious lag on two of them.


Symptoms​


  • Main display (DVI) → 60 Hz, perfectly smooth.
  • Two secondary displays (HDMI) → only run at 30 Hz, laggy/slow redraw (especially noticeable when moving windows or using Pro Tools).
  • Nothing hardware-wise has changed (same cables, converters, etc).
  • The RX 580 is correctly recognised in About This Mac and System Report.
  • The issue began only after moving from Mojave to Monterey.

What I’ve tried​


  • Installed Martin Lo’s OpenCore EFI (successfully using MountEFI etc).
    → Booted fine, but no improvement to the lag / refresh issue.
  • Reset PRAM after installing Martin Lo EFI → no change.
  • Verified that Metal support appears enabled in System Report, but performance suggests no full hardware acceleration.

My questions​


  1. Has anyone experienced similar 30 Hz / no hardware acceleration behaviour with an RX 580 on Monterey?
  2. Are there known fixes — e.g. specific OpenCore or GPU firmware tweaks — that restore full acceleration across all outputs?
  3. Would performing a fresh install of Ventura (using OCLP again) potentially help, or does this sound like a driver / firmware limitation under Monterey?

Any insight or success stories would be hugely appreciated — I rely on all three displays for Pro Tools automation and editing, so smooth GPU performance is essential.


Thanks very much for any help or experience you can share!
 
Have you tried uninstalling post-install root patches and reinstalling post-install root patches?
 
I use inexpensive 4K TVs as monitors, and they always have HDMI inputs. Even if I start from a DP connection, it goes to HDMI.

HDMI has been fussy for me. Try going into the monitor menu, find the hardware port setting, and manually set it to HDMI 2.0 mode. That's how I got 4K60Hz working on my systems. The "auto" setting was apparently failing to 1.4 mode, instead of 2.0 mode.

You can also try rebooting a monitor after booting the computer up. If the menus offer a restart function. Or pull the power cord if need be. (don't pull and reinsert HDMI cables regularly - ports are only rated for so many insertions). This forces macOS to reset the video connection while the full drivers are loaded.
 
reader50 said:
I use inexpensive 4K TVs as monitors, and they always have HDMI inputs. Even if I start from a DP connection, it goes to HDMI.

HDMI has been fussy for me. Try going into the monitor menu, find the hardware port setting, and manually set it to HDMI 2.0 mode. That's how I got 4K60Hz working on my systems. The "auto" setting was apparently failing to 1.4 mode, instead of 2.0 mode.

You can also try rebooting a monitor after booting the computer up. If the menus offer a restart function. Or pull the power cord if need be. (don't pull and reinsert HDMI cables regularly - ports are only rated for so many insertions). This forces macOS to reset the video connection while the full drivers are loaded.
Click to expand...
Thanks - worth a look. I'll see if my screens have any HDMI options.
 
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