First it will run exactly as all other 980Ti-SLI configs out there (Just look at some benchmarks/reviews). The CPU will not bottleneck the GPUs but the PCIe Lanes will by a very small factor. Both cards will only run with PCIe x 8 because the i7 4790k only has 16 lanes overall. I don't know why you choose the old Devil's Canyon CPU instead of the newer Skylake CPU but it doesn't make much of a difference anyways. Your build is funny, you choose the old architecture (CPU/RAM) combined with the most powerful GPU config on a mid range class mainboard and one of the most expensive PSUs out there.