Intel Core i9 10940X's Advantages
Higher specification of memory (DDR4-2933 vs DDR4-2666)
Larger memory bandwidth (93.8GB/s vs 41.6GB/s)
Higher base frequency (3.3GHz vs 2.9GHz)
Larger L3 cache size (20MB vs 12MB)
Intel Core i5 10400's Advantages
Released 7 months late
Integrated graphics card
Lower TDP (65W vs 165W)