Intel Core i3 9300 's Advantages
Higher base frequency (3.7GHz vs 3.5GHz)
Intel Core i3 12300 's Advantages
Released 2 years and 9 months late
Higher specification of memory (4800 vs 2400)
Larger memory bandwidth (76.8GB/s vs 37.5GB/s)
Newer PCIe version (5 vs 3.0)
Larger L3 cache size (12MB vs 8MB)
More modern manufacturing process (10nm vs 14nm)
Lower TDP (60W vs 62W)