Intel Core i9 7900X 's Advantages
Larger memory bandwidth (79.47GB/s vs 76.8GB/s)
Higher base frequency (3.3GHz vs 2.5GHz)
Intel Core i5 12400 's Advantages
Released 4 years and 8 months late
Integrated graphics card
Higher specification of memory (DDR5-4800 vs DDR4-2666)
Newer PCIe version (5.0 vs 3.0)
Larger L3 cache size (18MB vs 14MB)
More modern manufacturing process (10nm vs 14nm)
Lower TDP (65W vs 140W)