The Intel Core i9-14900 is the objective winner of this comparison, securing victory in nine out of fourteen measured specifications. Its most significant advantage over the Intel Core i5-8400 is its L2 cache, which is 2033% larger. While the Intel Core i5-8400 maintains a 70% advantage in Max Turbo Power, the superior cache capacity of the Intel Core i9-14900 establishes it as the more capable component across the majority of the evaluated technical categories.

Users prioritizing high-capacity cache for complex processing tasks should select the Intel Core i9-14900 to leverage its substantial architectural lead. Conversely, the Intel Core i5-8400 is the appropriate choice for those who specifically require the efficiency profile offered by its Max Turbo Power advantage. By evaluating these two distinct technical strengths, buyers can align their selection with either the cache-heavy performance of the newer model or the power-focused characteristics of the older unit.