The AMD Ryzen 9 3900X is the objective winner of this comparison, securing a lead in eight out of fourteen measured specifications. Its most significant advantage over the Intel Core i5-12600KF is its L3 cache capacity, which is 220% larger. This substantial memory buffer provides the primary technical edge for the Ryzen 9 3900X, establishing it as the superior option based on the total count of winning specifications across the evaluated categories.

Users prioritizing the massive L3 cache advantage should select the AMD Ryzen 9 3900X for their build. Conversely, those who place a higher value on the Intel Core i5-12600KF should choose it for its specific strength in L2 cache, where it holds a 58% advantage. Your final decision should depend on whether your workload benefits more from the superior L3 cache capacity of the Ryzen or the enhanced L2 cache performance offered by the Intel processor.