The AMD Ryzen 9 7900X3D wins in 9 out of 14 comparable specs. Its biggest advantage is L3 Cache (700% better).
Ryzen 5 8600G wins in 5 specs (NPU Performance: 100% better).
Recommendation
Choose Ryzen 9 7900X3D if you want the best overall performance — especially l3 cache.
Choose Ryzen 5 8600G if npu performance matters more to you.
