Put the matching pair of RAM modules in two of the slots that are the same color. For example, one pair goes into the blue slots, the other pair goes into the black slots. It's the same way with my MSI motherboard. To verify download and run CPU-Z and under "memory" there should be something that says "channels #" and it should say dual. http://www.cpuid.com/downloads/cpu-z/1.57-setup-en.exe
It's the purple download button, not the big green one at the top.