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2017 5k i7-7700k 4.2G iMac with two T3 ports - Can I use two eGPUs?
 

2017 5k i7-7700k 4.2G iMac with two T3 ports - Can I use two eGPUs?  

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BoostMyMac
(@boostmymac)
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Joined: 1 month ago
 

New here but have combed through many forum posts before joining and appreciate all of the input and time saving tips people have shared.

I just bought a Razer Core X Chroma with Radeon 7 to help boost the 4k editing in FCPX.  As the title notes I am working with a 2017 iMac and would like to know if I am able to use another eGPU in the second T3 port?

From what I have gathered so far, its hit and miss being dependant upon your Mac.  In my case I am on the latest Catalina Mac OS.  From what I have found it appears my iMac has one T3 controller with two ports.  I ask this question because in the article published by 9to5 Mac https://9to5mac.com/2018/08/14/back-to-the-mac-010-dual-egpus/ they say this

"I learned something new while filming this episode: the 2018 MacBook Pro can handle up to four eGPUs — two eGPUs per Thunderbolt 3 bus — simultaneously. On the MacBook Pro, or iMac Pro you can connect eGPUs to any of the available Thunderbolt 3 ports. I briefly dabbled around with connecting four eGPUs to my MacBook Pro, and needless to say, it was downright absurd."

This made me wonder if my iMac is capable of connecting two eGPUs and work.

If anyone can confirm one way or the other if this would work with my Mac it would be greatly appreciated.

Thanks.

2017 5k iMac - i7-7700k 4.2GHz boost to 4.5GHz 64G RAM
Razer Core X Chroma - Radeon 7


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mac_editor
(@mac_editor)
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Joined: 3 years ago
 

@boostmymac

You can, but Final Cut Pro doesn’t use multiple eGPUs (only multiple internal/slotted GPUs). In most cases, having two eGPUs is pointless unless for some very specific needs. 

purge-wranglerpurge-nvdaset-eGPU
2018 MacBook Pro 15" RP560X + RX 5700 XT (Mantiz Venus)


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BoostMyMac
(@boostmymac)
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Joined: 1 month ago
 

@mac_editor

Thank you for the clarification.

Darn, I was hoping it could because I need more GPU power.  I thought with the Catalina update they were supporting multiple eGPU's in FCPX.  I must of overlooked the exact wording of what that meant for FCPX.

So the only people that can take advantage of multiple eGPU's for FCPX are the Mac Pro crowd.  If so, that is very disappointing.

Thanks for your confirm and quick reply.

2017 5k iMac - i7-7700k 4.2GHz boost to 4.5GHz 64G RAM
Razer Core X Chroma - Radeon 7


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BoostMyMac
(@boostmymac)
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@mac_editor

I was thinking over your response to my question regarding multiple eGPU support for FCPX.  It did get me to think of maybe another option based upon your previous answer that said FCPX can utilize two internal GPUs to improve performance of FCPX, especially with recent 10.4.7 and Catalina update.

Here's my questions:

If I were to buy a 2013 Mac Pro and installed two Radeon 7's would FCPX then use both when rendering?  I am not sure dual Radeon 7's can be used anyway because from the research I did it doesn't appear AMD supports mGPU configuration for them, but it does for the Vega 56 and 64 variants.  They are both Vega 10 architecture and Radeon 7 is Vega 20.  I am just not sure if that matters or not to FCPX.

With the new FCPX and Catalina updates Apple mentions support for multiple GPU's like the Radeon Vega II and Duo versions.  Since Radeon 7 is a Vega 20 architecture and the two I mentioned are same but far more powerful, I am thinking the dual Radeon 7s might be supported but without having the new Mac Pro released yet I just dont know.  I have one Radeon 7 already being used in eGPU with iMac but am willing to look at using 2013 Mac Pro and get another Radeon 7, both being used internally at that point.  Would the dual Radeon 7s work like I am hoping or are only T2 Mac Pro's with the more powerful cards able to pull off the multiple GPU support?

Thanks

This post was modified 1 month ago

2017 5k iMac - i7-7700k 4.2GHz boost to 4.5GHz 64G RAM
Razer Core X Chroma - Radeon 7


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mac_editor
(@mac_editor)
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Posted by: @boostmymac

If I were to buy a 2013 Mac Pro and installed two Radeon 7's would FCPX then use both when rendering?  I am not sure dual Radeon 7's can be used anyway because from the research I did it doesn't appear AMD supports mGPU configuration for them, but it does for the Vega 56 and 64 variants.  They are both Vega 10 architecture and Radeon 7 is Vega 20.  I am just not sure if that matters or not to FCPX.

@boostmymac I presume we are talking about installing Radeon VII internally for the 2013 Mac Pro? I don’t know if that’s doable but if it can be done it would be an interesting experiment. Maybe a nicer solution is to emulate the eGPU as an internal GPU. In my patch investigations, I did come across a way to do this but did not proceed further (patch was volatile).

I would say it’s not worth the effort and just waiting for the 2019 Mac Pro is better to gain more insight. 

purge-wranglerpurge-nvdaset-eGPU
2018 MacBook Pro 15" RP560X + RX 5700 XT (Mantiz Venus)


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BoostMyMac
(@boostmymac)
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@mac_editor

yeah, I was thinking of internal install of Radeon 7.

I noticed @itsage has some interesting findings with multiple eGPUs.  Seems there is an issue with Radeon 7 sleeping in all eGPUs except the new Nestor which he talks about that is yet to be released.  I dont think I have experienced that with my Razer Core X Chroma yet.

It makes me wonder if Apple is waiting to release another Catalina or FCPX update as Mac Pro is released that would further the quasi support for eGPUs.  The Mac Pro and the optional graphics power upgrades makes me think they are very serious about supporting the content creation community, albeit the ones with deep pockets.

It might as you say be best to wait for Mac Pro release and see what if any changes come about to support more eGPU use.  Knowing the MO of Apple, the only further support will be for their overly expensive new Mac Pro and graphics cards/Afterburner.

Your emulation of eGPU as internal GPU sounds very interesting.  From your earlier investigations into this did it sound like it would be viable or have a shot at stability?  

2017 5k iMac - i7-7700k 4.2GHz boost to 4.5GHz 64G RAM
Razer Core X Chroma - Radeon 7


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mac_editor
(@mac_editor)
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@boostmymac

@itsage did not find FCPX using multiple eGPUs, as did I. Only optical flow analysis uses all GPUs. I’ve been on FCPX for last 5 years.

https://egpu.io/forums/pro-applications/final-cut-pro-finally-gets-new-metal-engine-and-gpu-selection/

Posted by: @boostmymac

Your emulation of eGPU as internal GPU sounds very interesting.  From your earlier investigations into this did it sound like it would be viable or have a shot at stability? 

It was a fully functional patch and the eGPU was detected like an internal device (at least in System Report) and there was no eGPU icon and Prefer External GPU (which only shows up if eGPU is detected) option for apps. By volatile I meant it could break easily across macOS updates. At the time I didn’t feel it had any worth (since this FCP update was not released), but I guess I can test again. It is still unclear how Final Cut Pro would utilize multiple internal GPUs (let alone emulated eGPUs). Additionally, while the eGPU looked like it was being correctly emulated as an internal GPU, I don’t know how good the emulation was (you can partially emulate some aspects - I don’t know if I was emulating all then) - would apps actually see it as an internal device or not. 

This post was modified 1 month ago

purge-wranglerpurge-nvdaset-eGPU
2018 MacBook Pro 15" RP560X + RX 5700 XT (Mantiz Venus)


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BoostMyMac
(@boostmymac)
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@mac_editor

My experience so far with FCPX 10.4.7 and Catalina when using my Radeon 7 and eGPU it uses 100% of Radeon 7 when rendering most things from what I can tell through Activity Monitor.  What I find annoying is when I am rendering 4k with multiple effects the Radeon 7 is essentially doing all the work while my CPU (64GB RAM) is idle at 2-5% usage and my onboard 580X is fairly dormant.

I definitely can tell a difference now with using the eGPU with Radeon 7 but it seems to me Apple doesn't make any efficient use of CPU or my 580x while Radeon 7 is grinding away at 100% capacity.  I would think Apple would balance the efficiency of rendering and other background activities by using some CPU and 580x power that is sitting dormant.  Everything would go so much faster imo instead of me having to look at other options to increase my processing power when using FCPX.  I have plenty of unused power sitting dormant that should be put to work.  I would think they would make FCPX utilize a combination of all GPUs and CPU power to get the job done, similar to what goes on with RAM virtualization not to mention what DaVinci Resolve capability with multiple eGPUs.

So far my experience with FCPX and Catalina update is a bit sketchy.  Sometimes CPU kicks in and helps along with 580x and sometimes they are just dead dormant while I am tasking Radeon 7 at 100%.  The how and when FCPX decides to use CPU and internal graphics power isn't great imo when used with a powerful external like Radeon 7 and eGPU.  I know the eGPU gives the Radeon 7 a haircut of about 20-30% performance which I don't have issue with, its Apples odd implementation of how all CPU and GPU sources are utilized or lack thereof.

The new Mac Pro on the way gives me some hope that if that is supporting multiple internal GPUs that might open the door for older Mac Pros to use them too to full potential.  That would peak my interest in obtaining an older Mac Pro and maxing GPU power internally, but I'm also not hip in going backwards on a very old mobo and technology just to gain a little more GPU power.  

I don't edit for a living so buying a new Mac Pro makes zero sense, although I wouldn't complain having one.

I still don't have a full understanding what @itsage did with his new but not available Nestor eGPU and being able to use 4 eGPUs.  Maybe its just a Mac mini or iMacPro thing that can be done.

2017 5k iMac - i7-7700k 4.2GHz boost to 4.5GHz 64G RAM
Razer Core X Chroma - Radeon 7


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mac_editor
(@mac_editor)
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@boostmymac

It’s not that simple to program for multiple CPU/GPUs and distributing workloads across different resources with different constraints and capabilities is a challenging problem to solve. It might not make sense to non-programmers, but say in your example, sharing compute between the CPU and GPU isn’t a good idea as memory transactions are required. Do a variety of tasks at once and you’ll see parallelism. You can’t expect for anything and everything to use anything and everything because CPU + GPU does not always equate higher performance (there are many constraints). One of the primary goals of Metal is to reduce as much CPU use as possible and optimize performance on GPU. We are seeing the benefits here (you can do other things on the CPU while GPU keeps busy). You give Resolve as an example, but if you investigate, you’ll see that performance scaling is far from perfect on eGPUs and it’s all diminishing returns the higher the number of GPUs you go (yes performance increases but by how much and for what cost). I don’t know what level of performance you are hoping to find, but it seems that at least in the Mac ecosystem, your demands could only be met with the 2019 Mac Pro accelerator card.

Posted by: @boostmymac

I still don't have a full understanding what @itsage did with his new but not available Nestor eGPU and being able to use 4 eGPUs.  Maybe its just a Mac mini or iMacPro thing that can be done.

Nothing new. 4 eGPUs have been usable since Mojave (and daisychaining works too). Multi eGPU support is app dependent, not OS (since it already supports this). The Netstor enclosure does not cause sleep issue with Radeon VII. That’s all. To make it clear, there is no multi-eGPU support in FCPX.

purge-wranglerpurge-nvdaset-eGPU
2018 MacBook Pro 15" RP560X + RX 5700 XT (Mantiz Venus)


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BoostMyMac
(@boostmymac)
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@mac_editor

Yes, the Mac Pro Afterburner card would be a big help unfortunately its likely only to work in a Mac Pro and not a eGPU.  I have no doubt it will also be an expensive piece of hardware regardless what it works with.

I am curious though, if one could have two internal GPUs (Radeon 7s) and placed with lets say i9-9900k, what percentage level of performance improvement would you estimate could be had vs just one Radeon 7 in FCPX as it stands now?  30%, 50% or....?

From a programming standpoint I think Apple's view of the long game doesn't include much support for eGPUs in the future.  

 

 

2017 5k iMac - i7-7700k 4.2GHz boost to 4.5GHz 64G RAM
Razer Core X Chroma - Radeon 7


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