Xeon E5540 's Advantages
Higher specification of memory (1066 vs 3)
Lower TDP (80W vs 130W)
Intel Xeon X5680 's Advantages
Released 11 months late
Higher base frequency (3.333GHz vs 2.533GHz)
Larger L3 cache size (12MB vs 8MB)
More modern manufacturing process (32nm vs 45nm)