Xeon X3440 's Advantages
Higher specification of memory (1333 vs 3)
Higher base frequency (2.533GHz vs 2.4GHz)
Intel Xeon E5645 's Advantages
Released 6 months late
Larger L3 cache size (12MB vs 8MB)
More modern manufacturing process (32nm vs 45nm)
Lower TDP (80W vs 95W)