Should I upgrade my Ryzen 3600 or RTX 3070 first for smoother 1440p gaming?

If you’re already considering replacing both major components, a newer platform paired with a Radeon 9070-class card would be a much larger overall upgrade than buying only a 5800X3D. A 7500X3D-class processor should provide much better frame-time consistency, while the newer GPU would raise average FPS and give you more headroom for demanding 1440p settings. The main question is budget: if you want to keep the existing motherboard and DDR4 memory, upgrade the CPU first; if you can afford a platform change, the newer CPU-and-GPU combination is the more significant long-term move.

The GPU is also worth considering, especially if your goal is higher average frame rates rather than just eliminating stutters. Instead of spending heavily on a 5800X3D, you could use a less expensive Ryzen 5 5600X and put the savings toward a newer graphics card. That gives you a more balanced system, although the 3070 should still perform reasonably well at 1440p with optimized settings and DLSS Quality or Balanced.

The Ryzen 5 3600 is probably the main cause of the stuttering and poor 1% lows in this game. A Ryzen 7 5800X3D would be a substantial drop-in upgrade on your current AM4 motherboard, but a Ryzen 5 5600X or another affordable X3D chip could also provide a big improvement for less money. The RTX 3070 is still capable at 1440p with DLSS, so I’d start with the CPU and consider a graphics card upgrade later if you still want higher average FPS.