THANKSYou can get up to GTX 2070/GTX 2080 with 450watt PSU.
Wattage Usage with these build @ 1440p
CPU: OC i9-9900k @5ghz
GPU: GTX 2070
RAM: 32GB DDR4 3200
So You pretty much good with Ryzen 2 2700 Non OC + GTX 2070
RX 580 Consume more Wattage than GTX 2070/2080.. If your PSU Can run RX 580, it can run GTX 2080.