I also would suggest a single card upgrade rather than going for an SLI bridge. Running two cards on paper looks like it should double performance but in the real world it doesn't unfortunately. A multi card configuration creates a latency issue when splitting and re-stitching the workload back together. Historically this made for some minor screen tearing and while certain fidelity metrics will increase you still have to deal with the CPU bottleneck issue (which ultimately defines FPS anyways.) The SLI bridge was an improvement over just passing it back and forth via PCI-e but even with SLI there were still issues. Plus it is a real pain in the rump to setup and support. There was a real reason that Nvidia made dual chipped flagships during that time in history. It was like getting the boost of two cards without the issues of having two cards. The generational performance gains of even the least of a 3000 series card will out run multiple 900 series, plus you get directx 12, driver support refresh, and API goodies that 900 series cards don't have.