A splitter is only suitable for outputing the same signal to all connected monitors. For a triple-monitor surround setup with G-SYNC, you need to connect all the monitors to 3 DP ports on the same graphics card (HDMI is limited to 60Hz refresh rate and no G-Sync capability). For a massive 7680X1440 resolution using three PG278Qs, unfortunately two GTX 970s in SLI are still under-powered for what you want to do. I'd suggest two of the latest high-end graphics cards for the job. Make sure the graphics cards have 3 DP ports.
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