seems u want to know ALL about AMD Athlon K8 series today
Athlon K8 came with on chip MCT controllers with 64-BIT and 128-BIT width memory controllers.
those that were with 64-BIT have data through put of 3.2GB/s
and those 128-BIT are with 6.4GB/s
this is not what operating systems runs at, this is data throughput from the processor core to the on-chip memory controller, higher rate = faster operation.