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Dhanad Dipta avatar image
Dhanad Dipta asked ·

Nvlink support

I want to invest in 3x 2080 or 2x 2080ti to help speed up my lookdev workflow.

1) Do Arnold GPU support Nvlink for these GPU configurations?

2) main reason for multi gpu setup is to able to stack memory so that I can use large scenes and textures for my work. Is Arnold GPU capable of utilizing such multi gpu setup using nvlink for expanded memory?

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Declan Russell avatar image
Declan Russell answered ·

Hi Dhanad,

1) Yes, Its important to remember though that you can only NVLink two of these cards together at the same time. So if you had 3 x 2080 then you could only NVLink 2 of these cards together leaving the 3rd alone. This is important to remember as if you are using all 3 to render then we can't pool the memory of the 3rd non-NVLinked card, therefore you will be limited by the memory of that card. That being said, you could use a single card just for your display and the other two just for rendering which would reduce the contention between arnold and your display. Regardless of this 2080Ti's have more memory which one could argue it more important anyway.

2) Yes, Arnold will pool the memory of both cards if you use NVLink.

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Dhanad Dipta avatar image
Dhanad Dipta answered ·

Another question. If decide to go with just 2x2080ti and Nvlink them, will I be able to leverage 11+11 = 22GB as total memory for my GPU renders in Arnold? I know it wont be exactly 22, as some of it will be eaten by my OS, and display, etc. But that setup should still stack the 2 GPU memories correct?

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Dhanad Dipta answered ·

Thanks Declan,

To be sure, you are saying if I have 2x2080 (8gb memory each) nvlinked, and have a 3rd 2080 just for display/viewport use I can use the full 8+8 =16 gb of the two nvlinked card. This is ensured by manually selecting those 2 cards from the Arnold GPU settings tab for only rendering purposes, correct? If i intend to use all 3, you are saying Arnold will default to the 8gb memory because that's the memory capacity on the 3rd card? Correct me if my assumption is wrong.

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Correct. So if you select only the 2 NVLinked cards you would pool memory hand have 16GBs but if you select all 3 cards you would be limited to 8GBs because the memory that exists on the NVLinked cards would also need to exist on the single card.

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Thank you so much for your input!

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