DRagor :
Considering it's Evga 500 B indeed, I think you should have no problems from this side.
There's no way a 500B would power a 1070 under peak load. That thing will need to be replaced very quickly. The 500B is a tier 4 HEC unit - not in the same league at all as their much higher end G2 / P2 / T2 / G3 units. That's the thing with pre-builts - if they do not tell you the make and model of the PSU, DO. NOT. BUY. Under any circumstances. If you are even considering a pre-built, always, always inquire about the make and model of the power supply - because that is one of those things where they get you is by including low end junk that can barely power on, let alone power a high end GPU like the 1070. Cyberpower and some of the crap they sell on Amazon are notorious for this practice. I can't emphasize that enough.