Intel Core i5 12400T '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 (18MB vs 9MB)
More modern manufacturing process (10nm vs 14nm)
Lower TDP (35W vs 65W)
Intel Core i5 9400 's Advantages
Higher base frequency (2.9GHz vs 1.8GHz)