The Intel Core Ultra 9 285KF is the objective winner, securing victory in 11 out of 14 comparable specifications. Its most significant technical advantage is its L2 cache, which is 2567% larger than that of the Intel Core i5-8400. While the Intel Core i5-8400 maintains a 74% advantage in Max Turbo Power, the superior cache capacity of the Intel Core Ultra 9 285KF establishes it as the more advanced component across the majority of measured categories.

Users requiring the highest level of cache capacity should choose the Intel Core Ultra 9 285KF for their system build. Conversely, the Intel Core i5-8400 remains the appropriate selection for those who prioritize the specific Max Turbo Power advantage provided by that processor. Selecting between these two components depends entirely on whether your primary requirement is the expansive L2 cache of the newer model or the power profile offered by the older unit.