Evga brand name is not a guarantee of quality. Usually the oddball wattage s have better stats, 550w,650w etc. The 500w is almost always either the 500B or the 500W, both of which units are low end entry level units, consequently being made cheaper, using cheaper components, having minimal protections, lousy outputs etc, so tend to also have the lowest warranty and the highest rma rate.
While the wattage is sufficient to run a GTX 1070, it's always best to have some headroom if possible. During long gaming sessions or other periods of intense CPU / GPU usage, there's a possibility you might tax the PSU a little much.