its also cool if you have an unused gpu and a pcie-slot left since you can use that to run the frame generation instead of the main gpu.

frame gen always creates a little overhead that reduces the max frames a gpu cam natively render. you can offload this overhead to second gpu and may get a better result if the main gpu already struggles to get the required frames.

a friend of mine used that to be able to run monster hunter wilds with an acceptable framerate.