The Intel Core i5-12400 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 400% larger than that of the Intel Core i5-8600K. This substantial increase in cache capacity provides the primary performance edge for the newer processor, allowing it to outperform the older model across the vast majority of the evaluated hardware metrics.

Users prioritizing modern architecture and superior cache efficiency should select the Intel Core i5-12400 for their build. Conversely, the Intel Core i5-8600K remains a viable option for specific use cases that rely heavily on a higher base clock speed, where it maintains a 44% advantage. Choosing between these two components depends on whether your workload benefits more from the significantly expanded L2 cache of the newer model or the higher base frequency of the older unit.