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

[take_01.wav]

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!

 

[Bigwaff]

Have you tried uninstalling post-install root patches and reinstalling post-install root patches?

 

[reader50]

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.

 

[take_01.wav]

Have you tried uninstalling post-install root patches and reinstalling post-install root patches?

No - is that something that I can do via the OpenCore Legacy Patcher app, the uninstall bit I mean? I'll take a look. Thanks.

 

[take_01.wav]

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.

Thanks - worth a look. I'll see if my screens have any HDMI options.

 

[Jeeve Stubbs]

Maybe it's time to upgrade to a more recent Mac Pro?