Intel Xeon E5 2660 's Advantages
Released 3 years late
Newer PCIe version (3 vs 2)
Larger L3 cache size (20MB vs 8MB)
More modern manufacturing process (32nm vs 45nm)
Xeon E5540 's Advantages
Higher specification of memory (1066 vs 3)
Higher base frequency (2.533GHz vs 2.2GHz)
Lower TDP (80W vs 95W)