Xeon E6540 's Advantages
Larger L3 cache size (18MB vs 8MB)
Lower TDP (105W vs 115W)
Opteron 6308 's Advantages
Released 2 years and 8 months late
Higher specification of memory (1866 vs 1333)
Higher base frequency (3.5GHz vs 2GHz)
More modern manufacturing process (32nm vs 45nm)