In an effort to bolster system performance, Intel made the move to higher bandwidth DDR2 memory years ago but it wasn't enough to catch the Athlon 64 architecture. AMD didn't have the luxury (nor the need really) of supporting DDR2 memory, however. The K8's integrated memory controller architecture, while offering significantly better latency characteristics, would have to be completely overhauled, which meant a significant core rip-up, if the Athlon 64 were to be able to interface to DDR2 memory.



Link: Hot Hardware