Weirdly I've been running my tri-fire setup fro 6 years and never got BF1 or BF5 to run properly or smoothly or better with multi GPU, yet BF3 and BF4 were sublime. Currently running a 5700XT and for the first time in 15 years running a single GPU, doesn't feel right but have to admit, so much less hassle and I'm the biggest advocate for SLI/Crossfire ever, I've ran 2, 3 and 4 GPU's over the years and some titles it's incredible but I'd say in the majority cause more problems. Such a shame, as the premise is easy...Yes, contrary to popular belief and naysayers, SLI is actually supported by most major titles and works flawlessly in my experience. I play BF1 at 3440x1440 and it rarely dips below 90fps on ultra settings. It mostly stays above my monitor's 100Hz max refresh rate.
And my 6700K is still going strong. I might be tempted to go Ryzen at a later date but I'm in no rush. Will wait till DDR5 is commonplace first before investing in a new motherboard.
What nVidia and AMD shouid;'ve done is not rely on game support. They should've developed it that it was easier to implement instead of waiting for support... bit like AMD have done with the Image Sharpener, doesn't need anything from anyone else or development, it simply works. Greatest missed opportunity ever multi GPU was and one of the reason for building beastly systems for me.