Intel Xeon E5 2666 v3 's Advantages
Released 4 years and 8 months late
Higher specification of memory (2133 vs 3)
Newer PCIe version (3 vs 2)
Higher base frequency (2.9GHz vs 2.266GHz)
Larger L3 cache size (25MB vs 4MB)
More modern manufacturing process (22nm vs 45nm)
Intel Xeon E5507 's Advantages
Lower TDP (80W vs 135W)