It's not that they have "specific RAM slots for single and dual channel". A slot can't be dual channel by itself. It's the combination of two slots than can be dual channel, and many motherboards use color codings to state which pairs of slots will be run in dual channel.
In the case of your Asus motherboard, dual channel pairs are either the two yellow slots or the two black slots, ie: two memory sticks should be put in same-color slots if they are to run in dual channel mode.