Intel Core i5 9400F 's Advantages
Higher base frequency (2.9GHz vs 2.4GHz)
Intel Core i9 12900F 's Advantages
Released 3 years late
Higher specification of memory (4800 vs 2666)
Larger memory bandwidth (76.8GB/s vs 41.6GB/s)
Newer PCIe version (5 vs 3.0)
Larger L3 cache size (30MB vs 9MB)
More modern manufacturing process (10nm vs 14nm)