The AMD Ryzen 9 3900X is the objective winner of this comparison, securing a lead in seven of the fourteen evaluated specifications. Its most significant advantage over the Intel Core i9-13900K is its L3 cache, which is 78% larger. While the Intel Core i9-13900K holds its own in five categories, the overall spec-win count favors the AMD Ryzen 9 3900X as the more robust option across the majority of the measured fields.

Users who prioritize the benefits of a larger L3 cache should select the AMD Ryzen 9 3900X for their build. Conversely, those who require the specific advantages offered by the Intel Core i9-13900K should choose that processor instead, as it provides a 433% larger L2 cache. Your final decision should depend on whether your specific workload relies more heavily on the superior L3 cache capacity of the former or the expanded L2 cache of the latter.