and looking at the diagram for installing the memory, I found it pretty much self explanitory.

-if you only want to install 2 memory modules-you put it into slots 1 and 3

-if you have 3 memory modules-put them into slots 1, 3, and 5

-if you have 4 memory modules-running dual-channel, slots 2/1/4/3
-running triple-channel, slots 2/1/3/5

pretty easy to figure out if you have 6 memory modules

Just follow the diagram according to the manual

Note: it's not weird; it's just the way the motherboard is configured, not too different than installing DDR2 memory