SLI is dead. no one makes SLI profiles anymore and the drivers haven't made any progression with SLI for years. If you look at nvidia's cards, less and less have SLI pins now. i wouldn't be surprised if its completely obsolete next gen (RTX3xxx)
with a 1070, no, there are better cards available that will work in all use cases, if you can get a second card for peanuts do it but otherwise buy a higher spec card. With SLI it is always a question of is it worth it to YOU in the games you play rather than is it worth it generally (as that answer is the same for anything ultra high end and expensive and that is, rarely) quite a lot of games do still work well with SLI and means you can push 120fps @ 4k in max detail settings with high end cards but you have to accept in some games one card is all that will work. SLI is still necessary in my opinion, GPUs aren't fast enough but it needs to be fixed such that it works in all use cases. Can't see it gaining much traction anymore though, Nvidia has convinced people to pay big bucks for meagre performance from one card and the pool of people who want to buy a second mega expensive card for a handful of games is very small. DX12 was supposed to be the thing that saved multi GPU rendering, but its multi GPU support seems not to have come to much..
apart from this gen i always had sli, but support for it is b0rked most games released over the past 5 years not work well. VR games dont use sli. save your pennies or just get one beefy card
I have always had top end cards, after a few months with a 1080Ti it just wasn't enough, there wasn't a next step, 2 helped massively, I was due to switch out to the 2080Ti on launch but that barely out paces 2x 1080Tis when SLI works and I'm not buying two of those, getting tight in my old age Fortunately games rarely push graphical boundaries anymore and the 1080Ti is having quite a long life for me, though I do want more but I'd like a 50% jump at least for 2x the price.
