Memory Bus-speed. Definition?

Hej,

Følgende definitioner og ligninger er hentet hos Kingston memory. Det meste forstår jeg, men hvad er definitionen på
"Memory Bus Speed"?

DDR Memory Bandwidth:

(Memory Bus-Width) x (Data Rate) = Peak Bandwidth
(Memory Bus Speed) x (Operations/Clock-cycle/rate) = Data Rate

Each DIMM module is 64 bits wide, or 8 Bytes wide (each byte = 8 bits).

fx Peak bandwidth for PC3200 DIMMs:
(8 Bytes) x (400 MHz Data Rate) = 3,200 MB/second (3.2 GB/s).