Yes, its true that you can effectively increase performance of your PC by correctly configuring the RAM on motherboard. The Dual Channel mode, Triple Channel mode and all other modes are Motherboard specific. That is, you need a compatible motherboard for attaining any such modes. Let me take the example of the modern motherboards. Take a look at Asus M5A78L-M/USB3 Motherboard and you would make out that this motherboard is configured for Dual Channel mode.
In the above image, you can see that there are four available RAM slots. It is also clearly visible that out of these four, two are blue and rest two are black. So, if you were to setup a Dual Channel mode in this motherboard then you have to fix 2 DDR3 RAMs in either blue slots or black slots. But however keep in mind that if you put these 2 RAMs one after another, that is, one in blue and other in black slot, then you would not get Dual Channel mode, instead it will be the traditional single channel setup. And if you have 4 DDR3 RAMs then you can put the RAMs with similar frequencies in alternate position (either blue or black) to further increase the maximum throughput.
Like Dual Channel, you can also have triple channel setup but for that you will need to have a compatible motherboard that shows atleast three RAM slots with the same color. Moreover, several motherboards also support Quad channel setup but they are generally not considered by most of the gamers, reason being their high costs. So, if you intend to build a powerful gaming rig, I would simply recommend you to opt for Dual channel setup for its best price/performance ratio.