No 3 and 4 way SLI with GTX 1080 / 1070
"IMPORTANT UPDATE: After writing this story, but before publication, we went to NVIDIA for comment. As we were getting ready to publish, the company updated me with a shift in its stance on multi-GPU configurations. NVIDIA will no longer require an "enthusiast key" to enable SLI on more than two GPUs. However, NVIDIA will also only be enabling 3-Way and 4-Way SLI for a select few applications. More details are at the bottom of the story!
You'll likely recall that during our initial review of the GeForce GTX 1080 Founders Edition graphics card, we mentioned that NVIDIA was going to be moving people towards the idea that "only 2-Way SLI will be supported" and promoted. There would still be a path for users that wanted 3 and 4 GPU configurations anyway, and it would be called the Enthusiast Key.
As it turns out, after returning from an AMD event focused on its upcoming Polaris GPUs, I happen to have amassed a total of four GeForce GTX 1080 cards."