2 3080s or 1 3090, which config is better for Octane?

[ThetaGraphics]

While I’m currently a single-GPU limited free user (on 2 GTX 1080s), that could change, so in the interests of future-proofing:

Given that 3090s cost double that of 3080s (at least in a hypothetical world where scalpers don’t exist...) it would seem to me that 2 3080s would be a far more ideal configuration at a similar cost? (Although, would a 1000W PSU be enough? )

(Setting aside the VRAM argument (I know 2 3080s would be limited to 10GB, but I’m fine with out of core):

From a pure CUDA stand point, 2 3080s would have 17,408 cores compared to a 3090’s 10,496 cores.

However, I’ve seen that RT cores have a significant impact on render times as well, is Octane able to utilize all the RT cores on both cards like CUDA (2 3080s = 136 RTCs vs 1 3090 = 82 RTCs), or are they limited to one card like VRAM (2 3080s = 68 RTCs vs 1 3090 = 82 RTCs)?

Also, how do tensor core amounts affect Octane?

[Estebanmn]

Have I been wrong to assume Octane scales linearly as you add GPUs? All the performance tests I've seen come to that conclusion.

[Iceman9]

Gotta agree w/OP that if the scene doesn't require significant VRAM...that 2 3080's would be notably faster.

Pros/Cons stack up like this:

3080 x2
-2 3080's require 4 PCI slots (though careful, I think some after-market versions require 3...thus would consume 6 slots!)
-faster for most scenes

3090
-3 slots
-bit less energy
-faster with very high-poly scenes
-better for SIMs like Embergen

[ThetaGraphics]

Primarily what I want to know is whether this blue bar gets doubled with two cards or not.

[jimho]

newer version of OctaneBench is available now.
the 3080's score is 566,
if as usual, 2x3080will be arround 1132
https://render.otoy.com/octanebench/res ... owRTXOff=0

[Estebanmn]

Do you guys know what is this test that the Youtuber JayztwoCents ran in his review of the RTX 3090? https://www.youtube.com/watch?v=zxVwYbQ7Mdc

He doesn't give any details, but I don't really think he knows enough about the software to do so though.

[davorin]

I would definitively go for a RTX3090.....I intend to myself...

Draws less power than 2 * RTX3080 and uses up less slots...
Blower designs might be clocked lower...but you gain scalability...

And there's the 24GB VRAM. 10GB is nowadays already at the lower end....


For a rough PSU calculation I always use:

https://outervision.com/power-supply-calculator

[jimho]

I would wait and see if there is a 3080super or 3080ti which is rumored to be 20G Vram,
and hope it would be blower type.
the strugle with 2x3080vs 3090 is understandable, anyway it will be similar price but big OB difference:
2x3080:1115OB vs 3090:most likely700OB, it is big difference

[funk]

Do you guys know what is this test that the Youtuber JayztwoCents ran in his review of the RTX 3090? https://www.youtube.com/watch?v=zxVwYbQ7Mdc
He doesn't give any details, but I don't really think he knows enough about the software to do so though.

That scene uses 13GB of VRAM so goes to out of core on the 3080, making it about 10x slower. He mentions it on a pinned comment too

[Estebanmn]

Do you guys know what is this test that the Youtuber JayztwoCents ran in his review of the RTX 3090? https://www.youtube.com/watch?v=zxVwYbQ7Mdc
He doesn't give any details, but I don't really think he knows enough about the software to do so though.

That scene uses 13GB of VRAM so goes to out of core on the 3080, making it about 10x slower. He mentions it on a pinned comment too

Thank you. My bad, I missed that comment.