How should a GPU be paired with Ryzen 5 5600X3D for 1080p, 1440p, and 4K gaming?

  A 6-core X3D games best at 1080p with a mid-range card; 1440p works, and at 4K don't expect the CPU to help.

  When hunting used: prefer ones with warranty, check seller history, and run a stability test on arrival. If its price creeps near a new 5700X3D, take the latter — solid warranty beats nostalgia.