The Intel Core i7-12700K is the objective winner of this comparison, securing victory in ten out of fourteen measured specifications. Its most significant technical advantage is its L2 cache, which is 700% larger than that of the Intel Core i5-8400. While the latter component maintains a 66% advantage in Max Turbo Power, the superior cache capacity of the former provides a substantial architectural lead across the majority of the evaluated metrics.

Users prioritizing high-end performance and advanced architectural features should choose the Intel Core i7-12700K to leverage its massive cache advantage. Conversely, the Intel Core i5-8400 remains a viable option for those specifically seeking the efficiency benefits associated with its lower Max Turbo Power. Selecting between these two processors depends entirely on whether your primary requirement is the increased cache capacity of the newer model or the power profile of the older unit.