Do I need a gpu with Ryzen 9?
No, it doesn't have an integrated gpu. Processors with vega graphics are called apu's buy them if you don't want/require a discrete gpu. the Raven Ridge-based Ryzen 3 2200G and the Ryzen 5 2400G do have Vega Graphics integrated, while the Pinnacle Ridge-based Ryzen 5 2600(X) and Ryzen 7 2700(X) do not.
Does Ryzen 9 3900x have gpu?
there is no gpu built into the 3900x. so you need a graphics card to get ANYTHING to the screen.
What GPU is good for Ryzen 9 5900X?
GeForce RTX 3080
GeForce RTX 3080 One of the most special editions from the 3000 series is the . GeForce RTX 3080 It is the best competitive graphics card for Ryzen 9 5900X and the most sought-after GPU at the moment due to its superior 4K performance and delivery of better value than the flagship model.