His system power, max load will be roughly 550W.
1) System (no GPU) OC'd to 4.6GHz is roughly 350W.
2) GTX1070 OC max is probably about 200W.
*So I doubt your load will ever go above 75% on the PSU. No worries. This is a worst-case scenario. You'd rarely be using 100% CPU load while the GPU is doing the same.
Normal gaming load is probably near 50%.
Your MISTAKE is the GTX1070 calculation. I don't know where you got that. Perhaps that was TOTAL SYSTEM POWER for a Skylake build under load. (some reviews give graphics card draw, and some give TOTAL system draw)