Power-output of powersupplies are a bit overhyped.
You need about 200-250 watt for your system (mobo, CPU, mem and any other peripherals) with 1 classic HDD and 1 SSD. A typical gtx1060 takes about 125 watts. A 450watt powersupply would suffice for a system like this, and you can still add 1 or 2 HDD's to that.
However, a 1080ti for instance takes double that, 250watt. A 450watt supply will probably fall short here. If you plan on sticking to one card, I'd go for a 550 watt supply, maybe 600 (Depending on the price and features).
What's much more important is quality of the supply, go for 80 Plus gold or higher.