The Athlon II X4 645 is a fraction faster than the older 640 and we see much the same when comparing the Athlon II X2 265 to the 260. The Athlon II X3 445 produced a bandwidth of 12.1GB/s making it only slightly slower than the Phenom II X3 720. Finally the Phenom II X2 560 also provided a slight performance gain over the 555 model.
