What are memory module RANKS and how are they used ?

A RANK is a 64bit (or in a case of an ECC module 72bit) data width addressable area of a memory module. Currently a module can be: SINGLE RANKED (Rank 1) DOUBLE RANKED (Rank 2)QUAD RANKED (Rank 4).OCTO RANKED (Rank 8)1 RANK = 64bit width (or 72bit with ECC). Ranks are for interleaving to make a system run faster. This is where one device or part of a device is being accessed for data whilst another device or part of a device is getting ready to deliver data.