NVLink/SLI Combined Memory Not Fully Detected Upon Rendering

[jujubee]

I have two 2080 RTX with NVLink installed (formerly SLI.)
While I realize that the latest nVIDIA drivers do not directly support NVLink/SLI for 2000 series RTX cards, it's still available but has to be hard-coded into the software according to nVidia support.
Vidia did away with enabling the switch in graphics properties.
The memory is showing this as half of what I have when the cards are combined.
Other GPU rendering engines such as Octane do show the combined amount, so I know that it is working depending on the software being used.
If this could be implemented, it would be a great addition.

Thank you.

[Phillip Miller]

Vantage does not support NVLink for pooling the GPU memory between the cards, so the memory you see is that of a single card (which is correct).
Please note that you do not need to "enable SLI" or have a bridge between cards for Vantage to use the second GPU for additional performance.
For reference, V-Ray GPU does support memory pooling via NVLink.

- Phil

[npg]

There are already several forum threads on this subject. We don't combine the memory (requires complex code changes). We DO however benefit from the cards being linked as opposed to only using the PCI-express bus. The bus/link between the two cards is a bottleneck, so NVLink allows for higher maximum frame rates. If the framerate is low due to scene complexity etc. then the link won't make much of a difference.

[jujubee]

Thank you I am new to this software and it has been a while since I last used a chaos product after having switched to other GPU products. I also didn’t have too much time to look through other forum posts but will try in the future before asking here.

Question: is the faster and newer motherboard bus speeds perform better (v4) than an older motherboard (v3) using NVLink? I ask because I have an older computer with 2 2080 rtx plus NVLink and I have a new motherboard that hasn’t been installed yet. I’m just curious if they would perform better in the new (v4) motherboard (without using NVLink) than the v3 motherboard.

[Muhammed_Hamed]

Regardless of using NVlink or not, having a new motherboard/CPU with PCIe Gen 4 or Gen 5 is very helpful for Vantage. Specially if you run 2 GPUs
If your computer is very old as you describe, it will not just be a motherbaord. You will need to change CPU RAM and probably other components. You need to check

Best,
Muhammed

[npg]

If you look at the table here https://en.wikipedia.org/wiki/NVLink , it looks like the nvlink on 2080 should be about 3x faster than pci-e 3.0 and ~1.5x faster than pci-e 4.0, in theory. And just to reiterate, this is just the bus bottleneck. It being faster (wider bottleneck) does not automatically translate into higher frame rates.

[jujubee]

Removed post because it was confusing.