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2 Nvidia eGPUs working on an iMac Pro, 3...
 

2 Nvidia eGPUs working on an iMac Pro, 3rd doesn't work?  

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zacanowski
(@zacanowski)
Active Member
Joined: 1 year ago
Posts: 6
Apr 6, 2018 5:31 pm  

hi all,
I got 2 Sonnet 550 eGPU's with 1080 ti's working nicely with my Imac Pro, but I tried to add a third and all the boxes switch off when I log out, when all 3 are connected, and there's a black screen.
Does anyone have any ideas about how to get all 3 working, or why they don't? I'm on High Sierra 10.13.3 (17D2104)
Many thanks!
Zac

Pending: Add my system information and expected eGPU configuration to my signature to give context to my posts


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theitsage
(@itsage)
Famed Member Admin
Joined: 3 years ago
Posts: 4027
Apr 6, 2018 6:37 pm  

Most recent builds of macOS allow one eGPU per Thunderbolt controller. The iMac Pro has two TB3 controllers and therefore can handle up to two eGPUs. I have not found any official documentations from Apple on this but this has been the case with my testings as well as others.

Best ultrabooks for eGPU use

eGPU enclosure buying guide

94 external GPU build guides


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zacanowski
(@zacanowski)
Active Member
Joined: 1 year ago
Posts: 6
Apr 6, 2018 6:43 pm  

Thank you very much for your reply theitsage, that makes sense.

Pending: Add my system information and expected eGPU configuration to my signature to give context to my posts


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Flint Ironstag
(@flint-ironstag)
Estimable Member
Joined: 2 years ago
Posts: 166
Apr 6, 2018 8:38 pm  

Couple of other things:

- arbitrary MacOS limit of 4 GPUs, period (used to be higher than this a few versions back)
- recent Macs won't boot with more than 2 eGPUs attached, no matter what fashion, different TB buses, etc.

I have tested OSS Cube3 & Cube2, each with 2 Nvidia cards installed (1080s or 1070s at the time).  A 6,1 will boot with 2 cards in a single external enclosure, or with occasional futzing , 2 separate Cubes with 1 GPU each.  Adding a 3rd eGPU to the mix = no joy.

 

MP 6,1 | 4c | d700
MP 6,1 | 6c | d500


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zacanowski
(@zacanowski)
Active Member
Joined: 1 year ago
Posts: 6
Apr 6, 2018 9:30 pm  

Thanks for your info Flint - Bizon help also said there are not enough PCI-E lines for 3 eGPUs on Thunderbolt buses. It sounds like an amazing plan to have a box that holds more than one GPU. Do you think there may be any hope in the future? Just when I was getting addicted to GPU rendering it looks like I may have reached the limit until I get a different machine?

Pending: Add my system information and expected eGPU configuration to my signature to give context to my posts


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manji_fa
(@manji_fa)
New Member
Joined: 6 months ago
Posts: 3
Mar 24, 2019 12:06 am  

I’m trying to pm you to ask some suggestions about my iMac Pro.
it seems pm doesn’t work :/

iMac Pro 14 | 64GB | Vega 64


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Rafael Cichy
(@rafael_cichy)
Active Member
Joined: 7 months ago
Posts: 8
May 26, 2019 3:05 pm  

Hi together,
i was able to run 3 eGPUs with an iMacPro at the office. At home connecting the 3rd eGPU to my nMP was not so successful.  Every time i plug in the 3rd, all eGPUs instantly running the fans at full speed and the display went black. regardless with buses are used... i have tried so many variations, but still no luck.

did anyone has any suggestions for my scenario?

nMP 6.1 | 12 Core | 64GB | 2TB | D700 |
iMac Pro | 10 Core | 64GB | 1TB | Radeon Pro Vega 64 |
2x Mantiz Venus 2 | 1x Razer Core | 3x Radeon Frontier Edition |
Gigabyte Gaming Box RX580 |
OS X 10.14.5


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(@rhenriques11)
Eminent Member
Joined: 1 year ago
Posts: 39
May 26, 2019 4:58 pm  

Sometimes is a question of how you plug them. I was also facing the same problem in a MacPro 2013. Usually works if you plug at least two of them at exactly the same time. I also have more success when I plug them after a system login and then a logout. While in the users list, the plug in seems to be more successful.

Pending: Add my system information and expected eGPU configuration to my signature to give context to my posts


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Rafael Cichy
(@rafael_cichy)
Active Member
Joined: 7 months ago
Posts: 8
May 26, 2019 4:59 pm  

thx for the fast reply....

... i will give it a try right now.

nMP 6.1 | 12 Core | 64GB | 2TB | D700 |
iMac Pro | 10 Core | 64GB | 1TB | Radeon Pro Vega 64 |
2x Mantiz Venus 2 | 1x Razer Core | 3x Radeon Frontier Edition |
Gigabyte Gaming Box RX580 |
OS X 10.14.5


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OliverB
(@oliverb)
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Joined: 8 months ago
Posts: 1297
May 26, 2019 10:36 pm  
Posted by: rhenriques11

Sometimes is a question of how you plug them. I was also facing the same problem in a MacPro 2013. Usually works if you plug at least two of them at exactly the same time. I also have more success when I plug them after a system login and then a logout. While in the users list, the plug in seems to be more successful.

I cannot confirm this. I have been using 3 eGPU in MacOSX, too and there have been no issues at all. The necessity of a "logout" can come already with one single eGPU, but only for external display.

2018 15" MBP & 2015 13" MBP connected to RTX2080Ti GTX1080Ti GTX1080 Vega56 RX580 R9-290 GTX680


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Rafael Cichy
(@rafael_cichy)
Active Member
Joined: 7 months ago
Posts: 8
May 26, 2019 10:42 pm  

i've had not luck with this method. still the same behavior as i plugin the 3rd eGPU... i've tried different ports on different buses.

- even tried to daisychain one of them through a Thunderbolt-display.  

i don't get it...

nMP 6.1 | 12 Core | 64GB | 2TB | D700 |
iMac Pro | 10 Core | 64GB | 1TB | Radeon Pro Vega 64 |
2x Mantiz Venus 2 | 1x Razer Core | 3x Radeon Frontier Edition |
Gigabyte Gaming Box RX580 |
OS X 10.14.5


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