The Intel Core i9-14900KS is the objective winner of this comparison, securing victory in ten out of fourteen measured specifications. While the Intel Core i5-8400 maintains a notable lead in power efficiency with a 74% advantage in Max Turbo Power, the Intel Core i9-14900KS dominates in processing architecture. Its most significant technical superiority is found in the L2 Cache, where it provides a 2033% increase over the Intel Core i5-8400, representing the most impactful performance difference between the two.

Users prioritizing energy efficiency and lower power consumption should select the Intel Core i5-8400 for their build. Conversely, those who require maximum cache capacity for intensive computing tasks should choose the Intel Core i9-14900KS. By focusing on these specific advantages, buyers can align their hardware choice with either the power-conscious profile of the Intel Core i5-8400 or the high-capacity cache architecture offered by the Intel Core i9-14900KS.