Ohim is right. Whether it's CF or SLI, Multi-GPU usually causes a LOT of problems, which is why it's best to buy the single strongest GPU you can get, and only use 2 GPU's if there's nothing else better. (I.E. You have a 1080, and you can only get another 1080 to make things better)
Even then, there are SEVERE diminishing returns after 2 GPU's. The power draw, heat, and noise goes WAY up if you get 3 or more cards, while the amount of FPS you get (proportionally) goes WAY down.
So basically, 1 strong GPU is best, but if you have to multi-GPU, 2 is the most you should generally get. And getting the blower-style cards that blow hot air out of the case is optimal for CF / SLI. 2 of those are better than 2 custom coolers that just circulate hot air in the case (with the top card sucking in the hot air from the bottom one and getting hotter) until your case fans exhaust all the hot air. If you have to mix card types, blower should be on the bottom and the custom card should be on the top.
Anyhow, to reiterate: I feel like AMD's drivers are spot on lately, and it's wrong to blame them for CF / SLI problems which BOTH vendors have to contend with. Hell, Nvidia doesn't even allow you to do SLI with the 1060 on down anymore.