MP 7,1 Two W5700X Benefits?

[dspdoc]

Please forgive the noob GPU question, but is there any "horsepower" benefit to installing two W5700X MPX modules? Meaning, do they somehow combine their power (get seen and utilized as one), or is it totally pointless? I know that certain GPUs link together for a combined power boost. Just not sure how having two of these in my MP would benefit me outside of having the ability to use a ton of monitors, which I don't need to do. Thanks!

 

[deconstruct60]

Please forgive the noob GPU question, but is there any "horsepower" benefit to installing two W5700X MPX modules? Meaning, do they somehow combine their power (get seen and utilized as one), or is it totally pointless?

There is no core macOS pixie dust that gets sprinkled on them to make everything go faster. However, if an app explicitly sees them and can divide up the work to be done into two (or more ) parts substantantively decoupled from one another then should see performance benefits.

Not every app can. ( The Mac Pro 2013 ran into the apps only want one GPU issue. Typically, it is apps with an legacy design, tight coupled between display/frame processing and the computations , and/or sensitive to the data transfer latencies between the two cards. ). However, there are some that can.

I know that certain GPUs link together for a combined power boost. Just not sure how having two of these in my MP would benefit me outside of having the ability to use a ton of monitors, which I don't need to do. Thanks!

Really depends upon which apps do you use and which features in those apps can "spread the workload". If you apps can't then there is little upside. ( unless can 'pin' one resource heavy app to one card and another to the second card (and probably each with their own monitor attached. )

There is no automagical link -> boost effect for the MPX Vega II ( or two Solo or Duo) either. There is a faster link to swap data but it is still up to the application to explicitly identify the two GPUs and then deliberately orchestrate those two working together on a problem. ( that solves the problem where don't want to split up work because of sensitive to latencies. It does not solve the problem that the apps have to explicitly do the organizing. In that sense the W5700X isn't "loosing out" on being much harder to use in tandem. )

 

[dspdoc]

There is no core macOS pixie dust that gets sprinkled on them to make everything go faster. However, if an app explicitly sees them and can divide up the work to be done into two (or more ) parts substantantively decoupled from one another then should see performance benefits.

Not every app can. ( The Mac Pro 2013 ran into the apps only want one GPU issue. Typically, it is apps with an legacy design, tight coupled between display/frame processing and the computations , and/or sensitive to the data transfer latencies between the two cards. ). However, there are some that can.



Really depends upon which apps do you use and which features in those apps can "spread the workload". If you apps can't then there is little upside. ( unless can 'pin' one resource heavy app to one card and another to the second card (and probably each with their own monitor attached. )

There is no automagical link -> boost effect for the MPX Vega II ( or two Solo or Duo) either. There is a faster link to swap data but it is still up to the application to explicitly identify the two GPUs and then deliberately orchestrate those two working together on a problem. ( that solves the problem where don't want to split up work because of sensitive to latencies. It does not solve the problem that the apps have to explicitly do the organizing. In that sense the W5700X isn't "loosing out" on being much harder to use in tandem. )

Please correct me if I am wrong, but there are parts of your response that sound concerning. As if having two GPUs installed could actually cause problems and hurt more than it helps?

 

[tanoanian]

From what I understand video toolbox will use both cards if available. Plex is an example of an app that utilizes video toolbox for transcoding. Also, the 6,1 Mac Pro is not supported by video toolbox.

Video Toolbox | Apple Developer Documentation

Work directly with hardware-accelerated video encoding and decoding capabilities.

developer.apple.com

 

[deconstruct60]

Please correct me if I am wrong, but there are parts of your response that sound concerning. As if having two GPUs installed could actually cause problems and hurt more than it helps?

Not if used properly by the application. Multiple x86 cores can be used improperly by an application and could potentially lead to more problems, but nobody is seriously trying to move back to single core CPUs. Every substantive app you use has a 'bug list'. There is always some problem in vast majority of apps.

If the application doesn't go "look" for multiple GPUs then in most cases it won't find the other one. Many tens of thousands of Mac Pro 2013 models were sold and used. There were no wide spread implosion by apps due to the presence of two GPUs there. Lots of apps aren't even going to put in the work to assign work to the second GPU. Nothing "bad" happens if don't even use it. But the additional code to take advantage of them is also more work for the application developer to do. Some won't put in the effort ( not enough return on investment. ). Some apps don't have that much parallelism in large enough zones.

You are not going to get uniformly doubling of performance across all aspects of all apps.

If you use something like DaVinci Resolve which does scale well with multiple GPUs for several application functions than there is a better "bang for the buck". Final Cut Pro X can send some workloads there. If you use something like Adobe Illustrator for most workload then multiple GPUs doesn't do anything ( even the ones with Infinity Fabric connections between them... that largely won't add any magic dust value for that app). LogicX ... about nothing. Generic "games" ? ... no.

It is not a universal return on the additional funds spent. But that would be for any additional GPU ( that isn't particular to the W5700X. )

 

[deconstruct60]

From what I understand video toolbox will use both cards if available. Plex is an example of an app that utilizes video toolbox for transcoding. Also, the 6,1 Mac Pro is not supported by video toolbox.

Video Toolbox | Apple Developer Documentation

Work directly with hardware-accelerated video encoding and decoding capabilities.

developer.apple.com

The Mac Pro is out partially because there is no iGPU with Intel's Quicksync present. And that AMD and/or Apple really didn't target the limited video decode in the GPUs in the Mac Pro 6,1 (2013).

But also indicative that the app has to make the calls. This API allows the app to make a call to get a list of the decoders/encoders available. In this specific instance the Apple core library is delegating out the work. (e.g., that call to pro workflow decoders can route some decode work to an Afterburner card is present. So can be routed away from GPUs completely if the GPU/drivers don't support the de/encoding. ). But macOS doesn't provide a virtual GPU that is presents a uniform "one GPU" interference to 'merged' GPUs for all GPU APIs.

 

[OkiRun]

The Mac Pro is out partially because there is no iGPU with Intel's Quicksync present. And that AMD and/or Apple really didn't target the limited video decode in the GPUs in the Mac Pro 6,1 (2013).

But also indicative that the app has to make the calls. This API allows the app to make a call to get a list of the decoders/encoders available. In this specific instance the Apple core library is delegating out the work. (e.g., that call to pro workflow decoders can route some decode work to an Afterburner card is present. So can be routed away from GPUs completely if the GPU/drivers don't support the de/encoding. ). But macOS doesn't provide a virtual GPU that is presents a uniform "one GPU" interference to 'merged' GPUs for all GPU APIs.

Any idea how FCPX would recognize the presence of multiple Afterburner Cards? I wonder if the code would be like recognizing multiple GPUs... I also wonder how FCPX would know how to divide up work between the internal GPU, and two Afterburner cards. Yes ~ assuming you are using Pro Res.

 

[fhturner]

Any idea how FCPX would recognize the presence of multiple Afterburner Cards? I wonder if the code would be like recognizing multiple GPUs... I also wonder how FCPX would know how to divide up work between the internal GPU, and two Afterburner cards. Yes ~ assuming you are using Pro Res.

Yes, FCPX can make use of multiple Afterburner cards and multiple GPUs. It can use either up to 3 Afterburners, or that's what Apple has given info about, and each add'l card increases the number of streams it's able to play. Can't say for sure how it would divvy up workload between those and "internal GPU" (assuming you mean an MPX module or standard PCIe card on MP7,1), but I would imagine most decode/playback tasks are handled by the AB and some filters and effects are handled by the GPU.

And to respond back to the OP, a twin W5700X setup should have a benefit in some tasks, including this one (Final Cut Pro X). Even a dual Radeon HD5770 setup in a cMP will increase the speed of some rendering tasks. Just depends on what tasks and what apps take advantage...

 

[dspdoc]

Yes, FCPX can make use of multiple Afterburner cards and multiple GPUs. It can use either up to 3 Afterburners, or that's what Apple has given info about, and each add'l card increases the number of streams it's able to play. Can't say for sure how it would divvy up workload between those and "internal GPU" (assuming you mean an MPX module or standard PCIe card on MP7,1), but I would imagine most decode/playback tasks are handled by the AB and some filters and effects are handled by the GPU.

And to respond back to the OP, a twin W5700X setup should have a benefit in some tasks, including this one (Final Cut Pro X). Even a dual Radeon HD5770 setup in a cMP will increase the speed of some rendering tasks. Just depends on what tasks and what apps take advantage...

Thanks! Still researching to figure what all advantages there will be and on how many apps. I even messaged Blizzard to see if World of Warcraft would benefit from two cards and they couldn't give me a straight answer. That's the only game I really like to play.

 

[deconstruct60]

Any idea how FCPX would recognize the presence of multiple Afterburner Cards?

FCPX does not recognize them. The Apple Foundation API manages all access to the Afterburner card. The apps don't have to "do" anything substantively different if already calling the appropriate API.

"...
Up to three Afterburner cards will provide increased performance of ProRes and ProRes RAW decoding
..."

About the Afterburner accelerator card for Mac Pro (2019) - Apple Support

Apple Afterburner is an accelerator card for Mac Pro (2019), created to enhance Apple ProRes and ProRes RAW workflows for film and video professionals.

support.apple.com

You run out of x16 slots after three ( presuming have at least one x16 assigned to a GPU ). Also not really going to get x16 worth of bandwidth out of slot 4 either. How actually useful three cards seems a bit dubious in the context of actually trying to display those streams. Three decoders aimed at the 'input' of the sole remaining 'display' GPU seems likely to get clogged at some point ( same reason why Apple constrains the Afterburner to a x16 slots for sufficient bandwidth 'out' . ).

The Afterburner card is constrained to three 8K decode streams ( at 10 bit color at 30fps uncompressed that is about 40Gbps . 3 x 40Gbps is approximately the limit of x16 PCI-e v3.0 ). And contributing reason why Apple says max out at eight 8k streams instead of nine ( 3x3).

With an external expansion box and some external point-to-point PCI-e DMA transfers might be able to be more able to more practically use the output from three Afterburner cards decoding at full capacity, but I have doubts Apple's core libraries actually handle that well. Eight 8K streams to actual displays would need some explanation (without some recompression).

I wonder if the code would be like recognizing multiple GPUs... I also wonder how FCPX would know how to divide up work between the internal GPU, and two Afterburner cards. Yes ~ assuming you are using Pro Res.

No it won't because Afterburner is a system choice of whether to do the decode via software or hardware. So the decoding is abstracted ( virtualized) . As long as it non-8K ProRes shouldn't really need to fall back on the CPU decoder for any reasonable number of decode streams if had two Afterburner cards.

I have a suspicion that multiple Afterburner cards is more about keeping the load well below max on any single card so can run constant loads for longer times. The loads are just distributed round-robin as come in.

The GPUs are not completely abstracted away from the applications. There is a layer handled by the drivers so not dealing with raw hardware, but not to the point don't have a "handle" on individual resources (GPUs in this case).
[automerge]1590156312[/automerge]

Thanks! Still researching to figure what all advantages there will be and on how many apps. I even messaged Blizzard to see if World of Warcraft would benefit from two cards and they couldn't give me a straight answer. That's the only game I really like to play.

No. Apple doesn't have a "see as one GPU" API for games ( or one synthesized frame buffer) . There is no gaming advantage on previous or this Mac Pro in macOS. Highly doubt Apple is going to put any effort into gaming for dual GPUs in macOS any time soon either. Apple never supported SLI or Crossfire previously either. Not going to start now ( via Infinite Fabric ... which the W5700X doesn't even have. ). [ There is a substantial number of hiccups that come along with trying to spread load and still keep highly real time refresh constraints, that Apple graphic stack has stayed away from as 'unnecessarily complex' feature to chase. Apple has problems enough keeping the graphics stack stable with the general targets they have traditionally addressed. ]

Multiple GPU on macOS is going to be almost exclusively going to be a Pro app computational feature. Looking in other categories is likely largely a waste of time. If buying two in search of an app to use them most likely means don't need two. Folks with apps that can use them generally know at this point whether more than one is helpful.

 

[goMac]

Also unless you are really going nuts with World of Warcraft, you only need one W5700X. Maybe if you are trying to run in 6k... But a W5700X can handle World of Warcraft at 5k no problem.

 

[dspdoc]

Also unless you are really going nuts with World of Warcraft, you only need one W5700X. Maybe if you are trying to run in 6k... But a W5700X can handle World of Warcraft at 5k no problem.

Thank you!

 

[LEOMODE]

Thank you!

I use W5700X and WoW works 60~80fps at 4k resolution with settings at 10. But when I connect 4 displays (3 4k + 1 1080p) it starts to lag down to 40-50 fps. But the main problem is W5700X ramps up fans a lot when I play it. My post here:

W5700X MPX ramping up fans frequently

Not sure if it's a hardware issue or driver issue (hope it's the latter), but whenever I play a less demanding game such as World of Warcraft on either Boot Camp or Mac OS 10.15.6, the GPU usage easily gets up to 90+% and Mac Pro fans ramp up really hard for a quick 10-15 seconds or so). But it...

forums.macrumors.com