..

[juli_19]

what is single channel mode

 

[slhpss]

single channel means there is one path of communication for the RAM essentially.. dual channel uses 2 paths to effectively double available bandwidth for the memory to communicate along and so on and so forth for tri channel and quad channel

 

[clutchc]

It means you are only getting about half the speed out of your RAM you could. It requires matching sticks in the correct pair of slots to utilize faster dual channel mode.
http://www.hardwaresecrets.com/article/133