I just bought parts for upgrading my pc ,essentially a new build. All together cost me 650$ and i get a consistent 1440p - 180fps at ultra. But i’m playing on a tv monitor, so my next upgrade is there.
Mid-size micro atx compatible tower
B450ds3h motherboard
Ryzen 5 3600 cpu (you don’t need much better than this for a gaming pc)
Sapphire pulse 8gb Rx 580 gc
600w power supply (80 plus bronze)
16gb memory 3200mhz
512 gb nvme ssd (as long as you go ssd, you’ll be fine)
And a 1tb hdd for excess storage
With your budget, I’d have upgraded the ssd to at least 1tb, gotten a full size tower, gone with a radeon rx 5700 or nvidia rtx 2060 super and bought a bigger/better motherboard such as an x570 full atx board for about 300$ more than i spent, and that’d leave around $ 250 for a new 144hz monitor without going much over 1.2k.
Already have enough mice, keyboards and headsets to equip a small e-sports team though, so that’s where i didn’t have to budget.