Intel Core i5 6600 's Advantages
Higher base frequency (3.3GHz vs 3.0GHz)
Lower TDP (65W vs 125W)
Intel Core i9 13900K 's Advantages
Released 7 years late
Higher specification of memory (DDR5-5600 vs DDR4-2133)
Larger memory bandwidth (89.6GB/s vs 34.1GB/s)
Newer PCIe version (5.0 vs 3.0)
Larger L3 cache size (36MB vs 6MB)
More modern manufacturing process (10nm vs 14nm)