DIMM RAM Slots in ASUS H97M-E

[cauliear]

I dont really understand DIMM (dual inline memory module) explantation in this motherboards manual. Should I stick ram into A1 and B1 or A1 and A2 ?
Here is ss from manual:
http://imgur.com/lXxXEfD

 

[Calvin7]

If you want dual channel, use (A1 and B1) or (A2 and B2).
If you want single channel, use (A1 and A2) or (B1 and B2).

 

[danitkd]

Can i use 4gbx3 (total 12gb) configuration? And What slots should I use?