The Intel Core i5-14400 is the objective winner of this comparison, securing victories in nine out of fourteen measured specifications. Its most significant technical advantage is the L2 cache, which is 533% larger than that found in the Intel Core i5-8400. This substantial increase in cache capacity represents the primary performance differentiator between the two processors, providing the newer model with a clear architectural lead across the majority of the evaluated categories.

Users prioritizing modern architectural efficiency and increased cache capacity should choose the Intel Core i5-14400 for their system builds. Conversely, the Intel Core i5-8400 remains a viable option for those specifically seeking a lower Max Turbo Power, as it holds a 56% advantage in that particular metric. Selecting between these two components depends on whether your requirements favor the expanded cache resources of the newer processor or the power profile of the older model.