MP 7,1 Mac Pro 7,1 + "cheap" 6900XT + Pro Display XDR

[Canubis]

I am thinking about upgrading my setup to a new Mac Pro 7,1 + Pro Display XDR. (I may wait a few more weeks because of the rumors of Apple possibly speed bumping the current MP.)

The price Apple asks for the W6900X seems ridiculous compared to retail prices of a RX 6900 XT – the latter even seems to perform better under some tests seen at barefeats.com.

Is there any downside or anything speaking against a setup like this:
- Mac Pro 7,1 with cheapest Apple GPU option 580X
- Sapphire Nitro+ RX 6900 XT (this model seems to still exactly fit; read other models can be too large)
- Pro Display XDR connected to the 580X / or RX 6900 XT directly (if possible ?)

 

[VelNZ]

Hey, I'm in the exact same same boat. Just purchased an XDR as the first step because it will work with my MBA and MBP and hopefully at 4K with my 2010 Mac Pro with RX 560. I'm also waiting for the Intel refresh of the Mac Pro 7,1/8,1 rather than the AS refresh because Intel will be supported for at least 5 years (+2 years security updates) and after that time I should be able to install native linux on it which may not be possible with AS.

Anyways, regarding your question, I think the main difference would be that the third party GPU will be a lot noisier, so that's something to consider depending on your workspace.

 

[randy85]

I've got a 7.1 w/ Pro Display XDR running with MPX W5700X and a Gigabyte 6800 XT in combination.

It all works fine. I have the MPX module running the display. I'm pretty sure the gaming cards won't be able to work with the Pro Display in 6k.

For me the fan noise of the card is pretty subdued. I can barely notice it (albeit in a room that isn't totally silent). I'm happy with the purchase.

One thing I did notice is that in Resolve, I get better performance if I disable the weaker W5700X gpu for compute and just use it for display. It seems like perhaps the software caps the usage to match the weaker card or something along those lines.

So I would check how the software you use handles multiple GPUs.

 

[joevt]

The XDR should work fine with a 5000 or 6000 series GPU because they support DSC. Use a Belkin Charge and Sync cable or other method to get both DisplayPort and USB 2.0 to the display.
If it doesn't work, then it's because Apple broke something. There's other threads that discuss the XDR and non-MPX module GPUs.

 

[flowrider]

I'm running a Gigabyte RX6800XT with an LG 24" UltraFine. I use this cable:

Monoprice Bidirectional USB Type-C to DisplayPort Cable - 4K@60Hz, Black, 6ft - Monoprice.com

No longer will you be limited by the direction of your cable! This Bidirectional USB-C? to DisplayPort? Cable allows you to connect your legacy DisplayPort devices to your newest USB-C enabled display

www.monoprice.com

My 24" is a 4K monitor. I've heard, but no experienced that 6K wont work. However, I believe that if you run two cables you will get you 6K.

Lou

 

[joevt]

However, I believe that if you run two cables you will get you 6K.

What two cables? DisplayPort input comes from Thunderbolt or a DisplayPort cable. There's no two cable connection except that Thunderbolt carries two DisplayPort connections for GPUs that don't support DSC.
Maybe you mean USB+DisplayPort like with the Belkin Charge and Sync cable. I think the USB connection is only required for USB features of the display (brightness, presets, USB ports).

 

[flowrider]

^^^^Sorry, I thought the XDR had two TB inputs. Looks like it only has one? Even my LG has two inputs. However, the XDR does have DSC? I think that should run @ 6K with the BiDirectional cable.

Lou

 

[Canubis]

Thanks guys for all your input! Highly appreciated!

I somehow assume having the XDR connect to the MPX module and not the 6900XT directly may cause decreased performance in some apps - or is it nothing to worry about? What happens if the XDR is connected to one of the TB ports on the top of the Mac Pro - without the MPX and just the third party 6900 XT installed?

I also found some other threads here but mostly with slightly other setups (egpu boxes, iMac etc) and with mixed results that seem a bit "hacky" tbh. One eg. could only reach 5k resolutions.

Is there anyone who actually has such a setup with a Mac Pro + a Pro XDR directly connected to the 6900XT already running and could confirm (how exactly) it works?

 

[ondioline]

Connecting the XDR to an MPX port will use that video card, not your 6900XT (this should be obvious lol)

No MPX means theres no DP output on the internal ports at all.

 

[Canubis]

Connecting the XDR to an MPX port will use that video card, not your 6900XT (this should be obvious lol)

My initial thought was as well, that is obviously how it would work.
But an app could still use the 6900XT for rendering and just use the MPX module card to kinda "passthrough output" the result, no? At least that’s what I know is possible when using egpus. You can tell macOS to prefer the external card, even though a display is connected to the internal card On eg. a MacBook. So I am wondering if there is any significant downside to this performance wise vs. a direct connection.

 

[ondioline]

It's not exactly like the 'prefer external gpu' option. Yes you can tell Blender or FCPX or whatever to use the 6900XT, if it has that capability. MacOS won't automatically shift the acceleration to the 'better' card though in other circumstances. It's only going to use the card that is outputting the display as the accelerator. Exactly the difference between connecting a monitor to a port on the back of your eGPU vs the MBP.

 

[flowrider]

Ya know, there is another option. A few of the third party cards have a USB-C output. One off those cards is the Reference AMD Card.

Lou

 

[joevt]

Ya know, there is another option. A few of the third party cards have a USB-C output. One off those cards is the Reference AMD Card.

Apple says those USB-C ports might not have full functionality on the 6000 series cards. I'm not sure why that would be if AMD follows the XHCI spec like they did with their 5000 series cards.
https://support.apple.com/en-ca/HT208544

So if you want USB functionality from the XDR, then you might have to use USB-C of 5000 series card or go with the Belkin Charge and Sync cable or similar method.

 

[flowrider]

^^^^Before my Gigabyte RX6800XT I had an AMD Reference RX6800 and used the USB-C output with a quality USB-C cable and it worked just fine. It did not work with a TB cable.

And, again, you can use the BiDirectional cable I linked above. I am using the cable right now with my RX6800XT.

Lou

 

[joevt]

^^^^Before my Gigabyte RX6800XT I had an AMD Reference RX6800 and used the USB-C output with a quality USB-C cable and it worked just fine. It did not work with a TB cable.

And, again, you can use the BiDirectional cable I linked above. I am using the cable right now with my RX6800XT.

Apple said it was a wake from sleep problem, so maybe everything else about the USB-C port is fine. Makes sense it wouldn't work with a TB cable but it should work with USB-C cables (that support 10 Gbps USB) and Thunderbolt 4 cables (which are supposed to support everything).

Bidirectional cable will work but you'll be missing the USB features of the display (presets, brightness control, USB ports).

 

[flowrider]

^^^^Yes. To control brightness I use Monitor Control. I don't use the USB ports on my monitor. I have tried and still have the Belkin cable. IHO, it's a very long cable and bulky. It does work though and provides the features you list.

Lou

 

[joelypolly]

I got the 6900XT Nitro and its only had display port connectors, the highest resolution it will do is 5K unfortunately since MacOS doesn't support DSC

 

[joevt]

I got the 6900XT Nitro and its only had display port connectors, the highest resolution it will do is 5K unfortunately since MacOS doesn't support DSC

Did you try it with the XDR?
Did you try creating an override with the DisableDSC flag?
https://forums.macrumors.com/threads/amd-radeon-rx-6800-xt-6900-xt-for-macos.2262295/post-30381590

 

[joelypolly]

Did you try it with the XDR?
Did you try creating an override with the DisableDSC flag?
https://forums.macrumors.com/threads/amd-radeon-rx-6800-xt-6900-xt-for-macos.2262295/post-30381590

Yeah it's on my XDR its still 5K with the Belkin cable. I haven't tried creating an override but everything I read says Apple disabled the feature in Big Sur

 

[joevt]

Yeah it's on my XDR its still 5K with the Belkin cable. I haven't tried creating an override but everything I read says Apple disabled the feature in Big Sur

Overrides are disabled for M1 Macs (you can at least override the display name and maybe some other stuff but not the EDID).
Overrides still work on Intel Macs.

 

[joelypolly]

Overrides are disabled for M1 Macs (you can at least override the display name and maybe some other stuff but not the EDID).
Overrides still work on Intel Macs.

This is on my Mac Pro 2019 and it doesn't seem to be working unfortunately. I assume when you said overrides you mean the patch-edid.rb file and then editing it to add the override key/value pair?

 

[joevt]

everything I read says Apple disabled the feature in Big Sur

Did you mean DSC? I thought you meant overrides.

This is on my Mac Pro 2019 and it doesn't seem to be working unfortunately. I assume when you said overrides you mean the patch-edid.rb file and then editing it to add the override key/value pair?

I guess that's one way to do. Post the result so we can check it. In the override, change the display name so that you know the override is being used.

 

[TrevorR90]

I just got a 6900 xt and took out my 580x. My XDR display works when plugged into the usb-c port of the card using the thunderbolt cable but I can no longer change brightness. Does anyone have any suggestions?

Funny enough, in bootcamp I can change the brightness of the XDR via the Bootcamp control panel but not in macOS.....

 

[flowrider]

^^^There are two ways:

1. Use this cable:

Belkin Charge and Sync Computer Connection Cable for HUAWEI VR Glass

Adapt HUAWEI VR Glass to connect with computer. Support DisplayPort high-speed transmission. Support HUAWEI VR Glass PC mode 3K 90Hz resolution. 4.5 meters in length, enjoy immersive VR games. 2 USB-A and 1 DisplayPort connet with PC, 1 USB-C port connects with Huawei VR Glass.

www.vmallworld.com

With that cable you will get the Brightness control in the Apple Control Panel

2. Use this software:

Download MonitorControl for Mac | MacUpdate

Download the latest version of MonitorControl for Mac for free. Read 8 user reviews and compare with similar apps on MacUpdate.

www.macupdate.com

This is an App that will allow you too change brightness.

Lou

 

[joevt]

I just got a 6900 xt and took out my 580x. My XDR display works when plugged into the usb-c port of the card using the thunderbolt cable but I can no longer change brightness. Does anyone have any suggestions?

Funny enough, in bootcamp I can change the brightness of the XDR via the Bootcamp control panel but not in macOS.....

The USB port on the 5000 series cards work in macOS for USB and display devices.
I don't know if the USB port on the 6000 series cards works for USB devices. Can you connect a keyboard or flash drive to it? If not, then go with the Belkin Charge and Sync cable or similar solution (such as Wacom Link Plus).