The Guru of 3D published a review on the GeForce GTX 1070 2-way SLI
A quote from the article:
We grab two MSI GeForce GTX 1070 Gaming X editions graphics cards and set them up in 2-way multi-GPU SLI. We'll obviously focus at Ultra HD performance as well as a micro stuttering analysis with the help of FCAT. Join us in this review where we'll once again look at everything.GeForce GTX 1070 2-way SLI Review @ Guru3D