Take a look at this Zester, I hope this helps...
If you need some further explanation just aks
(I hope this post correctly, I trying to add a PDF to this post)
This information is from the book entitled The 8088 and 8086 Microprocessors. Programming, interfacing, Software, Hardware, and Applications. Fourth Edition by Walter A. Triebel and Avtar Singh. Published by Prentice Hall
BTW I know this isn't the most up-to-date information but the basic principals haven't changed.
Also as I don't believe this excerpt talks about dual channel ram.
Dual Channel ram allows for the combination of the data pipes to double the bandwidth of the DRAM
I.E I have dual channel capable ram (you also need a dual channel capable mobo) DRAM in single channel mode its data pipe is 64 bits, in dual channel mode is 128 bits.
hope this helps...
Ram.pdf