Intel Xeon E5 2420 's Advantages
Released 2 years and 3 months late
Larger L3 cache size (15MB vs 8MB)
More modern manufacturing process (32nm vs 45nm)
Xeon EC5509 's Advantages
Higher specification of memory (1066 vs 3)
Higher base frequency (2GHz vs 1.9GHz)
Lower TDP (85W vs 95W)