Native 4K with Radeon 5500 XT

[Edhawk]

Just because the dGPU didn't make the cut and isn't on the newest buyers guide doesn't mean it is a bad buy. My PowerColor RX580 isn't on the list either and the card runs macOS beautifully.

The iMac Pro 1.1 relies solely on the discrete graphics card, the Xeon CPU's Apple use in these systems don't have an IGPU. If you have your IGPU and a discrete GPU enabled when running with a iMac Pro SMBIOS this can cause issues with the graphics.

Either of these setups would be better than your current mis-match:

• Disable the IGPU and continue with the iMac Pro SMBIOS, seems wasteful to me.
• Continue with the IGPU and dGPU enabled, and change your SMBIOS to an iMac 20.2. But run the IGPU with a Headless framebuffer. As recommended by the developers of WhateverGreen.kext for a system of this nature.

Personally I would go with the iMac 20.2 SMBIOS, with both GPU's enabled.

 

[geoffoliver]

I did disable the IGPU as it's not in use, but I'll try your suggested config and see what I get. Thank you!

 

[geoffoliver]

Same deal. Scaled resolution options for days, but the "best for" option is still a massive 1920x1080, and system information still thinks the monitor can do 5k.

 

[Edhawk]

Just working through a few thoughts.

The Graphics/Displays report shows your dGPU working through a x8 PCIe lane. I assume this is to support & share the x16 lane with the two PCIe M.2 slots. Do you use an M.2 drive in one or both of the motherboard M.2 slots, i.e x8 for the dGPU and x4 for each of the M.2 slots?

Your motherboard specification page - https://www.gigabyte.com/Motherboard/Z490I-AORUS-ULTRA-rev-1x/sp#sp states it has a 'PARADE PS175 chip'. This chip is additional to the IGPU and dGPU you are using. I assume Gigabyte have added this chip to assist the IGPU, when there is no dGPU present, as the board only has a single PCIe slot.

Do you have this chip enabled or disabled in your bios? As I am not sure how this chip would function in macOS. Not sure it can be disabled either, as the motherboard manual is fairly silent on the matter.

I believe this chip and the IGPU can support a 4096x2160@60 Hz display on the built-in HDMI 2.0 port, and
a 4096x2304@60 Hz display on the DisplayPort 1.4 port. So not to shabby for just an integrated GPU.

Your RX 5500 XT is supposed to support similar resolutions, according to the AMD specification page - https://www.amd.com/en/products/graphics/amd-radeon-rx-5500-xt.

Part of the issue with the resolution looking like 1920x1080, could be this card is aimed at gamers using the 1080P resolution. I like the little caveat AMD have included on the page, passing any differences between supposedly identical cards off on the manufacturers.

I assume your PSU is 450W or larger, as that is the minimum recommended for this card on a modern system.

 

[geoffoliver]

I am using both of the M.2 slots - one for the boot drive, and one for the broadcom card for wifi/bluetooth/airdrop/etc/etc.

I believe the PARADE PS175 chip is enabled in the bios -- the iGPU is and, much like the manual, the bios doesn't have any details about specifically enabling/disabling that chip, so I'm not really sure what the deal with it is. There's only options to enable/disable/"auto" the iGPU (mine is set to "enabled"), and to adjust memory settings for the iGPU.

I'll have to try the iGPU and see if it's any better than this dumb AMD card. I just tried popping the DP cable over into the iGPU port and got no signal, so I'm guessing I need to tweak my config.plist. Fun stuff!!

PSU is 650W -- https://www.newegg.com/fsp-group-hyper-m85-ha650m-650w/p/1HU-0095-00072?Item=9SIABP96N27304

 

[JerryM]

Maybe try to delete framebuffer-patch-enable and shikigva=80 and see what happens?

Headless framebuffers(where the dGPU is the display out) do not need framebuffer-patch-enable and framebuffer-stolenmem.

shikigva=80 is mostly related to iGPU performance as well and I won't bother using this.

Also I won't use layout-id here since I will acomplish the AppleALC audio injection in boot-arg, but anyway it's irrelevant to GPU configuration.

I noticed that in your config.list XHCIPORTLIMIT is set to be False and I don't know why.


I am upgrading to Gigabyte Z490 Aorus Ultra and i9-10850K soon and I can share my config.list once everything works.

 

[geoffoliver]

Well this is fun.

I enabled my iGPU, tweaked my config.plist to allow it being used (and to enable the framebuffer patch and framebuffer stolenmem), and what do you know, I can get video out of the iGPU over DP, but not HDMI. Unfortunately, it looked like complete garbage - everything was horribly blurry - even though the "best for display" resolution was showing at 2560x1440 resolution, which is exactly what I want/expect. I rebooted, and things got worse! All sorts of weird artifacts and glitches, it looked like the graphics card was dying or something. Very odd. So, I shut down, yanked the USB, and booted back into MacOS running the dGPU, and I'm back to square one.

The scaled 2560x1440 resolution from the dGPU looks far superior than the 2560x1440 resolution on the iGPU, which is so weird because I would expect that, since the iGPU is actually pushing a display at 2560x1440 resolution out of the box (which is what I want) that would have looked perfect, but alas, that is not the case.

Re: shikigva=80, I was under the impression that this was for fixing DRM (which it does for me), so that's why I've got it in there.

Re: XHCIPORTLIMIT - I'm not sure why it's False, either. I don't remember ever changing it, but according to the sanity checker, it's ok to be off, but you should "enable if you have USB issues", which I'm not having any USB issues really... Not unless you count thumb drives being unmounted during sleep. I thought this was an XMP thing, but there doesn't seem to be a setting that completely resolves the ejected drive issue. With it disabled, an internal SATA drive is unmounted/ejected when the computer goes to sleep (what?!), and with it enabled, USB drives are umounted/ejected when the computer goes to sleep.

Re: layout-id for audio - I tried all the layouts trying to get the front panel 2-in-1 (headphones + mic) audio jack on my case to work (side note, I don't even know what these "layouts" are or what they do), and nothing did, so the layout I have selected gives a relatively clean list of options in the "Sound" prefs pane, as well as everything but the front panel 2-in-1 jack working... I can get sound out of it, but nothing in.

 

[JerryM]

Well, it is the same case for me. When choosing 2560x1440, the display resolution shows 5120x2880 which is definitely inaccurate. I guess it just 'happens' to match with display's resolution (3840x2160) when choosing 1920x1080 since the display's resolution in system report is somehow calculated as 2x resolution of chosen UI.

In both setting, the text and images look sharpe to me, at least it never makes me be suspicious of the 4K resolution. On the other hand, it is basically overshadowed by a 5K iMac whose ppi is over 30% larger.

 

[czerwus]

Hello. You need to set SMBIOS to iMac19,2. This Mac has 21.5-inch 4k screen by default. System preferences will show your screen resolution properly then.

When you use SMBIOS with 5K screen, system by default render 5K output and need to rescale it to your desire resolution what could cause overall system performance slowdown.

 

[geoffoliver]

Hello. You need to set SMBIOS to iMac19,2. This Mac has 21.5-inch 4k screen by default. System preferences will show your screen resolution properly then.

When you use SMBIOS with 5K screen, system by default render 5K output and need to rescale it to your desire resolution what could cause overall system performance slowdown.

Very interesting. I assume it's OK that I have a 27" screen? It would be so awesome to get native 4k output on this thing, and crisp up this text a bit. I guess I know what I'll be doing this weekend

Thanks for the tip!!!