I am planning to buying an MSI MEG Z90 mobo. PcPartPicker says it "requires" a PSU with TWO 8-pin EPS connections. MSI says you only need ONE, unless you are overclocking. I DO plan to OC an I7-8700K a little (20-30%), but I don't know if that means I REALLY need a PSU with dual 8-pin EPS connectors (Corsair RM850i/EVGA G3 850) vs their step-down 650W models. I am planning to use a Noctua NH-D15S cooler because need a long-term (years) stability w/o worrying about leaks, refilling coolant, etc. So It's obvious(?) that I won't be OC'ing much. GPU: single RX 580 4GB.
I know the cost diff is small (compared to the rest of my choices), but advice from others would make me feel a LOT better about my choice. (I also don't want to raise my electricity bill a lot).