"In fact, Athlon 64 has no front side bus at all. The memory controller is integrated into the CPU and works at the full core frequency. The chipset is connected with the CPU via the Hyper-Transport bus working at 800MHz."
When you refer to the "chipset," do you mean the memory controller?
If you do, and the controller is cast on a separate die (but in the same package), then doesn't that mean the effective FSB cannot exceed 800MHz for now?
At the same time, wouldn't 800MHz be capable of controlling "DDR1600"?