Resolve and NVIDIA SLI

Rendering with SLI-bridge and 2 Quadros. Please scroll down for more infos.

Screenshot 2020-08-18 16.51.36.png (54.32 KiB) Viewed 4674 times

Perfect power play

Hello,
I would like to briefly describe my experience with NVIDIA and SLI here. According to Blackmagic, Resolve Studio does not support SLI. I have the following configuration:
Motherborad: AMD Crosshair Formular Z
CPU: FX9590 (5 GHz)
Grafic: 2 x NVIDIA Quadro 6000 24GB + SLI Bridge
I have disabled "Use GPU Scopes" and engabled "Use display GPU for compute". With this setting, both graphics cards work perfectly together with the CPU in parallel. I have published a rendering process with a screenshot here. I can't imagine better hardware support for my 8-12k projects. Maybe NVIDIA supports Davinci Resolve Studio? Who knows (smile).

Resolve does support multiple GPUs, but it doesn't use the GPU interconnects (SLI/NVLink), as their bandwidth is too low.

Screenshot 2020-08-18 16.51.36.png

Perfect power play

Hello,
I would like to briefly describe my experience with NVIDIA and SLI here. According to Blackmagic, Resolve Studio does not support SLI. I have the following configuration:
Motherborad: AMD Crosshair Formular Z
CPU: FX9590 (5 GHz)
Grafic: 2 x NVIDIA Quadro 6000 24GB + SLI Bridge
I have disabled "Use GPU Scopes" and engabled "Use display GPU for compute". With this setting, both graphics cards work perfectly together with the CPU in parallel. I have published a rendering process with a screenshot here. I can't imagine better hardware support for my 8-12k projects. Maybe NVIDIA supports Davinci Resolve Studio? Who knows (smile).

It is probably utilizing both graphics cards but not in SLI mode.

Many thanks for this clarifcation.

Hello,

Agent 83, may I ask a few more questions?

1. You say “SLI-Bridge”. Do you mean NVlink bridge physically connecting the two cards?

2. Some articles claim NVlink is not SLI, but an alternative:

https://www.gpumag.com/nvlink-sli-difference/

Am I reading that wrong, is it SLI?

Is SLI actually enabled on your computer? How?

3. If SLI is enabled, and Resolve is not supposed to work with SLI, how does Resolve see the cards? Is it two cards, or one? Does Resolve see the sum of VRAM for both cards, or just the VRAM of one card, as it usually does?

I would love to NVlink my 2 Titan RTXs, and at the very least, have Resolve treat the cards they way it normally does, while the bridge is installed, and let third party apps take advantage of the bridged cards.

There are some AI solutions I’d love to start crunching.

Thanks!

Purpose of SLI is to share rendering load by splittting framebuffer renders between cards, each card renders part of frame and result is combined in the end. This way only subsets of final frame have to be moved between cards to the one that displays result. It is a driver level functionality afaik and thus does not need explicit game/application support. Resolve processing is not based on this kind of rendering tasks where SLI has any benefit, so having the bridge on does not help Resolve in any way. Not sure what the current status is, some time ago suggestion was to remove the bridge due to it having side effects or something but I think currently it can sit there, it is simply not used.

NVLink has more functionality and will replace SLI. Besides other things NVLink also allows memory pooling where cards can access the vram of other cards when doing compute tasks etc. SLI has no such memory sharing. This must be supported by application, it does not work automatically behind the scenes. So Resolve must add support for it, afaik there is no nvlink support right now.

Hendrik, thank you! Best, most concise answer so far!

Hey guys,

It looks like R17 will now allow Nvlink! Waiting for the next batch from nVidia. I'll update you to see if it works.

Hey guys,

It looks like R17 will now allow Nvlink! Waiting for the next batch from nVidia. I'll update you to see if it works.

Should be interesting


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When I've started with Resolve R16 in 2020, I had two 2080 Ti with a NVlink and SLI enabled, Resolve does not utilize both GPU's if SLI is enabled. I've disabled SLI in the NVidia control panel and after that Resolve used both GPU's

currently have two 3090s, the second one not yet installed and also no NVlink for it (really stupid that they've changed the connector again). However when I get the new brige I will test it with SLI enabled if something changed in R17.