Opteron 2220 's Advantages
Higher base frequency (2.8GHz vs 2.533GHz)
Xeon E5540 's Advantages
Released 2 years and 1 months late
Higher specification of memory (1066 vs 2)
Newer PCIe version (2 vs 1)
More modern manufacturing process (45nm vs 90nm)
Lower TDP (80W vs 95W)