The Intel Core i9-12900K is the objective winner of this comparison, securing victories in nine out of fourteen measured specifications. Its most significant advantage over the Intel Core i5-6600K is its L2 cache capacity, which is 1300% larger. While the Intel Core i5-6600K holds a 62% advantage in Max Turbo Power, the superior cache architecture of the Intel Core i9-12900K provides a more substantial technical lead across the majority of the evaluated categories.

Users should choose the Intel Core i9-12900K if they require the extensive L2 cache capacity that defines its performance lead. Conversely, the Intel Core i5-6600K remains a viable option for those specifically prioritizing the Max Turbo Power advantage provided by its design. Selecting between these two processors depends entirely on whether your workload benefits more from the massive cache improvements of the newer model or the power-related characteristics of the older unit.