Taking the liberty of trimming @Zoid
's build with a less expensive (but still decent enough) B450 mobo, etc, to try to squidge in a case and a decent monitor within 1600 CAD budget.
Strongly agreed with the Ryzen 5 3600 recommendation too btw.
No Windows licence included - either further trimmings can be made (RX 5700 non-XT GPU?), or the OP can transfer one from an existing system perhaps.
Why 4k? If it's for gaming? Unless you only run certain kinds of less demanding games at carefully managed settings, you're not going to get a particularly good 4k gaming experience at this budget level. I'm not sure there's much point buying a PC that is expensive, but still can't really handle modern 4k gaming, to run games poorly on a budget monitor.
A 1440p high refresh monitor would be a much, much better fit. And would also be more economical re: future GPU upgrades.
CPU: AMD Ryzen 5 3600 3.6 GHz 6-Core Processor
($238.00 @ Vuugo)
Motherboard: ASRock Fatal1ty B450 GAMING K4 ATX AM4 Motherboard
($92.92 @ Vuugo)
Memory: G.Skill Ripjaws V 16 GB (2 x 8 GB) DDR4-3600 Memory
($106.99 @ Newegg Canada)
Storage: Crucial BX500 960 GB 2.5" Solid State Drive
($129.99 @ PC-Canada)
Video Card: Sapphire Radeon RX 5700 XT 8 GB PULSE Video Card
($509.99 @ Mike's Computer Shop)
Case: Fractal Design Focus G ATX Mid Tower Case
($72.99 @ Vuugo)
Power Supply: Corsair RMx (2018) 650 W 80+ Gold Certified Fully Modular ATX Power Supply
($104.99 @ Canada Computers)
Monitor: AOC CQ27G1 27.0" 2560x1440 144 Hz Monitor
($332.99 @ Amazon Canada)
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2020-02-18 19:12 EST-0500
As for the keyboard and mouse, whatever looks nice and budget-level on Amazon. You can always buy shiny peripherals as an upgrade down the line.