CPU: AMD - Ryzen 5 2600 3.4 GHz 6-Core Processor ($164.99 @ Amazon)
Motherboard: ASRock - B450M PRO4 Micro ATX AM4 Motherboard ($69.89 @ OutletPC)
Memory: G.Skill - Ripjaws V Series 16 GB (2 x 8 GB) DDR4-3000 Memory ($119.89 @ OutletPC)
Video Card: XFX - Radeon RX 580 8 GB GTS XXX ED Video Card ($189.89 @ OutletPC)
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2019-01-19 12:39 EST-0500
The only other thing you need to worry about is your current power supply. It needs to be a decent 450watt or better. I would personally get a 550 watt. If you are unsure of what you have or it is a lower then 450 then I would buy a Corsair CX450 or 550 (grey and white lettering not green model) or a Corsair CX450M/550M PSU.