From what i have seen in traditional computing. Memory, or DIMM Slots work in parallel. It may differ slightly being in a Lap top but overall i found it to be like this. A single channel memory architecture is composed of two Slots. 1 Active channel contains a Max of two banks. Each slot works side by side on 1 channel to store and buffer data. With this in mind, that means Dual channel architecture contains 4 Memory banks, Quad channeling contains 8 memory banks.
The 1st Dimm in each channel will determine the clock rate of the system bus. The second dimm in each channel allows for more addressing and buffering space. So to have a dual channel system, you need at least 2 memory modules. For quad channeling, you need at least 4 memory modules. Single channel minimum requires 1 memory module, In this case 1 stick of DDR3. The clock of the memory module is also determined by the CPU's memory controller.
The prime benefit of a multi channel memory Architecture is increased memory bandwidth. A higher memory bandwidth allows for faster Read and Write operations in traditional computing before needing to access the HDD via the paging file. Also as a result, you end up with more Buffering space due to the additional memory modules.
One stick of DDR3 1600 should have a theoretical max bandwidth of 12.8 Gigabytes of I/O bandwidth per second. This is calculated by multiplying the base clock of 1600MHZ X 8 bits. 8 bits being 1 byte of data. So single channel DDR3's memory bandwidth is 12.8 Gigs, Dual channel is 25.6 Gigs and quad channel is 51.2 Gigs of memory bandwidth respectively per CPU compute cycle.
Increased memory bandwidth will achieve faster computing results in applications that are written to take advantage of them. Heavy multi threaded apps are a plus, as well as some video gaming engines. The CPU and motherboard are limiting factors on Multi channel architecture as well as memory operation clocks, the HZ frequency.