Redshift is a GPU-based rendering engine, but how well does its performance scale when multiple video cards are used in a system?

Redshift is a GPU-based rendering engine, but how well does its performance scale when multiple video cards are used in a system?
Now that OctaneRender has been updated to support the Volta GPU architecture, how well does its performance scale when using multiple Titan Vs? And how does that compare to other popular rendering cards like the GeForce GTX 1080 Ti?
As of version 3.08, the Volta GPU architecture is now supported in OctaneRender. How does it stack up compared to other Titan and GeForce series graphics cards – in terms of both performance and value?
OctaneRender is a GPU-based rendering engine, so the bulk of the processing it does is carried out on the video cards in a system. Different processors and motherboards can impact the number of cards that can fit in a single system, but do they matter beyond that? Does the CPU itself have any impact on rendering speed/performance?
We’ve previously tested the new Hybrid Mode in V-Ray RT 3.6, which combines CPUs and GPUs in order to speed up rendering, on Intel’s Skylake X processors. This time around we are going to test on AMD’s Threadripper 1950X, and use even more powerful GPUs than before. We also take a look at GeForce GTX 1080 Ti vs Titan Xp performance.
New in V-Ray RT 3.6, Chaos Group has added Hybrid Rendering: the option to combine CPUs and GPUs in order to render images and animations even faster. We give an overview of how this works, and then explore the impact it can have on rendering speeds.
Benchmark results demonstrating that PCI-Express x8 vs x16 speeds don’t impact GPU rendering performance.
This article looks at several motherboard chipsets, including X299 and X399, comparing how well they handle performance scaling across multiple GPUs in the FurryBall RT benchmark.
This article looks at several motherboard chipsets, including X299 and X399, comparing how well they handle performance scaling across multiple GPUs in OctaneBench 3.06.2.