Intel Xeon E5 2665 's Advantages
Released 2 years late
Newer PCIe version (3 vs 2)
Higher base frequency (2.4GHz vs 2.266GHz)
Larger L3 cache size (20MB vs 4MB)
More modern manufacturing process (32nm vs 45nm)
Intel Xeon E5507 's Advantages
Lower TDP (80W vs 115W)