As I wrote yesterday, the NVIDIA GeForce GTX 1080 has two SLI fingers that are used simultaneously by the new SLI High Bandwidth bridge.
Now word is going around that the GeForce GTX 1080 may be limited to two-way SLI. Chris Bencivenga, Support Manager at EVGA, first confirmed the news at the EVGA forums but later removed his post.
According to EVGA, NVIDIA will not support three- and four-way SLI on the GeForce GTX 1080. They state that, even if you use the old, multi-way connectors, it will still be limited to two-way. The new SLI connector (called SLI HB) will provide better performance “than 2-way SLI did in the past on previous series”. This suggests that the old SLI connectors can be used with the GTX 1080, although with less performance and only for two cards.
Several hours ago, EVGA said an update about SLI support will be coming soon. As such, it's still unknown if the news was inaccurate or incomplete. One possibility is that it will still work, but that NVIDIA will no longer officially support it and dedicate its resources to optimizations for two-way SLI.