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MP 7,1 What is the likelihood of proper support for the RX 6950 XT?

A

andy89

macrumors 6502
Original poster
May 22, 2005
318
123
Kent, England
I'm looking at upgrading the GPU in my Mac Pro to something that is a bit more recent and finding a RX 6900 or 6800 XT is starting to get a bit difficult. It seems much easier to find 6950 and 6850s. As far as I can tell these cards have been out for a while, and Apple has had plenty of time to make the (seemingly minor) tweaks required for them to function with Mac OS. Does anybody know if support for these cards is on the way?

The cynic in me says that Apple won't add support for these cards, because they trounce the GPUs in the M2 Mac Pro, but they also claim to be a company that cares about their environment impact. If that's so I would think that they would be willing to make minor changes to prolong the life of these older Mac Pros. I understand support for NVIDIA GPUs is gone and probably won't be coming back, but it would suck to leave us out in the cold like this.
 
Unfortunately the chances are slim. With all Mac's currently on Apple silicon, Intel/AMD is being left behind.

Also, GPU upgrades require a new motherboard to support it. I doubt Apple will make any effort to upgrade a 2019 product. These are the latest GPUs that the 2019 Mac Pro supports.

Radeon 6600Unsupported
Radeon 6600 XT12.1 - Curr
Radeon 6700Unsupported
Radeon 6700 XTUnsupported
Radeon 680011.4 - Curr
Radeon 6800 XT11.4 - Curr
Radeon 6800 XT*unsupported (can be used with OpenCore in 11.4+)
Radeon 6900 XT11.4 - Curr
Radeon 6950 XT*unsupported (can be used with OpenCore in 11.4+)
 
Yeah I'm not expecting them to do anything crazy like release updated motherboards for the 2019 Mac Pro. It shouldn't be too much to ask for them to make minor changes to the drivers to support what is effectively a slightly newer revision of cards which they already support.

Other operating systems maintain a list of device IDs separate from the driver which can be easily updated by hand when a new hardware revision is released. Mac OS seems to make this needlessly painful.
 
andy89 said:
The cynic in me says that Apple won't add support for these cards, because they trounce the GPUs in the M2 Mac Pro, but they also claim to be a company that cares about their environment impact. If that's so I would think that they would be willing to make minor changes to prolong the life of these older Mac Pros. I understand support for NVIDIA GPUs is gone and probably won't be coming back, but it would suck to leave us out in the cold like this.
Click to expand...
That's exactly why they don't want you using newer GPUs - hence you keep using your old machine for longer and it makes the new and amazing Apple gadget look less than amazing.

Best you can do is ditch MacOS, use Windows 11 on Mac Pro 2019 and then use whatever GPUs you want, provided they fit.
 
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The 7.1, like the Trashcan and the iMac Pro is abandonware.
Another brilliant computer neglected and ignored by Apple.
Why?
Because they can.
And when the insulting AS Mac Pro fails they can finally put highest performance computing and it's need for up to date upgrades behind them and declare victory.
 
Used to have 7.1. (sold in 2023 for PC).

The OP’s current GPU of Radeon Pro Vega II Duo is a PCIe 3.0, whereas the 6950 XT is a PCIe 4.0 x16 card.

the main issue would be speed. Severe chance of bottleneck due to low bandwidth.
there’s also the issue of case size vs the GPI size.

  • Slot 1 & 3 each use 16 lanes of PCIe 3.0, for a total of 32 lanes
  • All the other PCIe slots (and Thunderbolt connections) share the remaining 32 lanes, by using 2 allocation pools of 16 lanes each. By default, macOS will automatically allocate the pools. But you can manually configure this
 
I just bought the 6900XT to slot into my 2019 Mac Pro for exactly the reason you mentioned - that it's starting to become difficult to find them and the price drop benefit seems to be over. I haven't noticed any bandwidth throttling due to PCI 3 vs 4. It's working very peachily:)
 
hovscorpion12 said:
The OP’s current GPU of Radeon Pro Vega II Duo is a PCIe 3.0, whereas the 6950 XT is a PCIe 4.0 x16 card.

the main issue would be speed. Severe chance of bottleneck due to low bandwidth.
Click to expand...

The 6950 is not fast enough for PCIe 4.0 to make a noticeable difference - and you'd need really specific workloads to hit that limit.

There are a lot of benchmarks out there - but PCIe 4.0 doesn't matter for anything in that gen. Most reviews show a 3080 with absolutely no performance change on 3.0 vs 4.0. PCIe 3.0 still gives enough bandwidth to completely replace the contents of the cards entire 16 gigs of VRAM several times a second - which is way way way more than most workflows are going to do. (Stuff like games and most pro apps do not constantly load gigs and gigs worth of data on the card every frame.)

4.0 has been mostly useful for SSDs which move a lot more data back and forth between the CPU than a GPU does.
 
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The difference between PCIe 3.0 x16 and 4.0 x16 is negligible for a GPU. In a few of Puget Systems' tests the 7900 XTX was faster at 3.0 x16 (so probably something other than PCIe bandwidth was affecting the score). Even PCIe 2.0 x16 (Mac Pro 5,1) has good enough bandwidth for most anything you would notice (should be equivalent to PCIe 3.0 x8).

www.pugetsystems.com

Impact of GPU PCI-e Bandwidth on Content Creation Performance

Installing add-in cards—like capture cards—can limit PCI-e bandwidth to the GPU. Does the reduction of PCI-e bandwidth harm performance in content-creation?
www.pugetsystems.com www.pugetsystems.com
 
Most apps load stuff into VRAM once at load and stream very little as they run. There can be exceptions of course - but bandwidth impacts transfers, not GPU performance. Unless your PCIe bandwidth is low enough to impact GPU command transfers, or you’re streaming tens of gigs of data a second, it likely won’t matter.

People get really wound up about PCIe bandwidth without really understanding what it does. For very high end computational situations where you are churning through hundreds of gigs of data it matters. Or an SSD where you are moving tens of gigabytes of data at a time.
 
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Maybe a bit off-topic, but related to MP 7.1 graphics performance in Ventura/Sonoma.:
I realized that on my Mac Pro 7.1 with AMD Radeon Pro Vega II the Apple Maps application has poor 3D performance in Ventura/Sonoma.

I did the following check:
1. Start Apple Maps
2. Fly to Manhattan
3. Zoom to complex 3D buildings
4. Press and hold ALT+LeftArrow (contineously rotate)

I get the following in Sonoma 14.1.2 (was the same in Ventura 13.6):

Apple_Maps_3D_Performance.gif



On some other forums users suggested it may due to internet speed, however a MacBook M2 Pro does the rotation very smoothly without any lag. In Monterey I did not have this problem. Everything was super fast as you would expect given the GPU power of the Vega II.

So my question:
Do you observe similar behavior?

Thanks in advance for testing!
 
For a moment, I was hoping I might have to literally fly to Manhattan to check it out:)

I did what you suggested; mine turns very smoothly indeed and I'm not on what you might consider a mega-fast internet line, it's a very average 400 Mbps down/ 120 up. I doubt it's your internet connection.

I'm using the 2019 Mac pro on 14.1.2, bog standard 3.5G 8 core xeon w, 96gb of ram, but I do have a Radeon RX6900XT.
 
doobydoooby said:
For a moment, I was hoping I might have to literally fly to Manhattan to check it out:)

I did what you suggested; mine turns very smoothly indeed and I'm not on what you might consider a mega-fast internet line, it's a very average 400 Mbps down/ 120 up. I doubt it's your internet connection.

I'm using the 2019 Mac pro on 14.1.2, bog standard 3.5G 8 core xeon w, 96gb of ram, but I do have a Radeon RX6900XT.
Click to expand...
Thank you very much for testing! It helps very much! So I think we can exclude fundamental data transfer flaws due to optimized code for unified memory optimizations of ASi. I also agree that the problem is not related to the internet connection speed. Your graphics card is certainly more powerful than the Vega II, however the Vega II should be powerful enough to handle the task smoothly. Actually the GPU activity monitor shows the Vega II at only <~ 2% i.e. it is basically idle. What performance level does your GPU activity monitor shows?

Maybe it is some a driver issue related to the Vega II. I already did clean all caches and preferences settings for the Maps application to no avail.

Thanks again!
 
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