nDisplay mGPU setup

Development Cinematics & Media Virtual Production
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Hello there,

I’m having issues setting up properly nDisplay for a cluster using mGPU - in short : I can’t find a way to dispatch a viewport rendering to a secondary gpu even after following steps described on https://docs.unrealengine.com/5.1/en-US/ndisplay-overview-for-unreal-engine/#multi-gpusupport

Here is the setup :

  • 2x Quadro P6000 (R513.91) + Quadro Sync II (v2.02), but they are not in SLI/NVLink.
  • Each GPU outputs a 4K screen
  • Unreal 5.1
  • nDisplay config is one cluster node with two viewports. One viewport’s GPU index is set to 0 and the other one to 1. The config setting regarding Multi GPU Mode is set to enabled.

With this setup, it seems that only one GPU is working for both viewports (on task manager GPU 0 is at 100% and GPU 1 at 0%), resulting in bad framerate.
I currently have a workaround to create two separate cluster nodes on same IP with only one viewport for each, and add the custom command line dc_gpu=0 or dc_gpu=1 for either instance. This is not ideal as I would like to avoid synchronizing some logic in my project.

I noticed that the nDisplay configuration export json file (.nDisplay) has no entry related to Multi-GPU mode, how is that supposed to be taken into account ?

Feel free to ask for more information, and thank you in advance for your help!

2 Likes
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I had the chance to test the same software configuration on 2x RTX Quadro A6000, and it worked out of the box! I suppose mGPU is not properly supported for Quadro P6000 as they are older?
Anyway, just wanted to add this information for anyone that reads this

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I’ll be trying your multiple cluster idea! Currently debating upgrading to the A6000 or 6000 Adas. Did you use NVLink for your A6000 test or just threw them in and it spread out GPU usage?

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Hi I know it s an old thread, but could you tell me if your ndisplay was outputting good frameRates with ue5 ? tks

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I am experiencing the same issue. The multi-GPU (mGPU) works correctly with the R515 line of graphics drivers, but it doesn’t work with other graphics drivers. Since UE 5.1, there has been a warning to use R535 or later versions, and as a result, I cannot use mGPU. Have you found a solution

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This is very interesting! We’re running Quadro P6000s as well, and are forced to run two nodes per machine. Did you ever get it to run on the old hardware, or just upgrade to A6000s?