The Intel Core i3-12100F is the objective winner of this comparison, securing victories in eleven out of fourteen measured specifications. Its most significant technical advantage is the L2 cache, which is 233% larger than that of the Intel Core i5-8400. This substantial increase in cache capacity provides the primary performance edge for the newer processor, allowing it to outperform the older model across the vast majority of the evaluated hardware metrics.

Users prioritizing modern architecture and superior cache efficiency should select the Intel Core i3-12100F for their build. Conversely, the Intel Core i5-8400 remains a viable option for specific workloads that rely heavily on a higher total core count, as it maintains a 50% advantage in that category. Choosing between these two components depends on whether your specific computing needs favor the increased cache capacity of the newer model or the higher core count of the older one.