Fans of extreme graphics setups, get your handkerchiefs ready. Nvidia is largely killing off its in-house support efforts for three- and four-way SLI. First, some background. During its Pascal announcement, Nvidia unveiled a new SLI HB (for "high-bandwidth") bridge that would be required for optimal GeForce GTX 1080 SLI performance at high resolutions. Later, in its GeForce GTX 1080 whitepaper, the company advised that two-way SLI would be the default supported multi-GPU configuration, and that three- or four-way SLI would require signing up for an "Enthusiast Key" that would need to be loaded into a GTX 1080 somehow.
That website never materialized, and now Nvidia appears to be dropping three- and four-way SLI support from future SLI profiles altogether. In a statement to PC Perspective, the company said that it's "focusing [its] efforts on 2-way SLI only and will continue to include 2-way SLI profiles in our Game Ready Drivers."
That discovery came after PC Perspective's editor-in-chief, Ryan Shrout, tried to enable four-way SLI on a test rig and found that only two of the installed cards were ganged together by the driver. Since Nvidia's promised website for generating those "enthusiast keys" still hasn't launched, Shrout reached out to the company for an ETA on the launch of that tool, at which point the company told him this surprising news.
In its statement, the company says that it'll still be creating three- and four-way SLI profiles for the common 3DMark Fire Strike, Unigine, and Catzilla benchmarking tools (and possibly others), but its work on support for higher-order SLI configurations will end there.
It's not all doom and gloom for fans of multi-GPU insanity, though. As Nvidia's statement points out, game developers using DirectX 12 Explicit Multi-Adapter mode (or what Nvidia calls LDA Explicit mode) can make use of more than two GPUs regardless of the availability of an SLI profile. Popular benchmarking title Ashes of the Singularity already includes support for this feature (albeit only with two graphics cards, for now), and Nvidia says it'll work with developers looking to harness more than two GPUs in their game to ensure those titles will still provide a good experience for 10-series GeForce owners.
From our perspective, it's difficult to get especially heartbroken over this news. Ever since our first tests of Quad SLI in 2006 and our evaluation of three-way SLI back in 2008, we've never felt that ganging together more than two GPUs has been a terribly useful way of increasing performance for real-world applications. Graphics technology has certainly come a long way since then, but multi-GPU micro-stuttering is real, and while Nvidia and AMD do what they can, even dual-GPU configurations still produce less consistent frame times than a single high-end GPU might. Extreme system builders might shed a tear over this news, but we doubt the vast majority of gamers will ever notice—or care—about this change outside of comment-thread flame wars.