The Rx570 can spike upto @ 225w, or slightly higher depending on the model, even with its rated 200w ceiling. Add @ 150w for everything else and your entire pc, at its heaviest gaming is pulling @ 400w or less. That'll run on a good quality 450w psu, but I'd not run it on a mediocre 450w, a 500w would be more desirable. Of course pricing on good quality 450w models often puts them on competition with good quality 550w models as that's the highest competitive bracket.
Good 450w - decent 550w recommended. Andyson has a couple of decent psus, but that's not one of them. The Evga BV500 is no better than a 500B (ughh) revamped (restamped). There are better choices, but those will depend on budget and sales location.