Yeah mine are color coded, and it looks like 1 and 3, 2 and 4. Odd thing is i have them in 3 and 4 now, and its running the game the best it has in awhile. Then again, the color coding might not neccessarily mean which banks work together on this mobo.
I've seen similar "oddity" on non-colour coded motherboards as well. For some reason the manufacturers want to populate the last slots first, i.e. the ones that are farthest from the CPU. Is it a cooling thing, I don't know. Anyhow, on 4 slot mobos and two sticks slot #1 is always empty.