The Intel Core i5-12600K is the objective winner of this comparison, securing victories in ten out of fourteen measured specifications. Its most significant technical advantage is the L2 cache, which is 533% larger than that of the Intel Core i5-8400. This substantial increase in cache capacity provides the primary performance edge for the newer processor, establishing it as the superior component across the majority of the evaluated hardware metrics.

Users prioritizing high-performance computing should choose the Intel Core i5-12600K to leverage its vastly superior L2 cache capacity. Conversely, the Intel Core i5-8400 remains a viable option for those who specifically require a lower Max Turbo Power, as it holds a 57% advantage in that category. Selecting between these two processors depends on whether your workload demands the expanded cache of the newer model or the power efficiency profile of the older unit.