The Intel Core i3-14100 is the objective winner of this comparison, securing victories in eleven out of fourteen evaluated specifications. Its most significant technical advantage is the L2 cache, which is 233% larger than that of the alternative. While the Intel Core i5-8400 maintains a lead in total core count, the superior cache capacity of the newer model provides a decisive edge across the majority of the measured hardware metrics.

Users prioritizing modern architecture and the substantial L2 cache advantage should select the Intel Core i3-14100 for their build. Conversely, the Intel Core i5-8400 remains the appropriate choice for those who specifically require the 50% higher total core count provided by that processor. Your final decision should depend on whether your specific workload benefits more from the increased cache size or the higher number of physical cores available.