By looking at that motherboard, I can assume that it doesn't support Dual Channel mode by making the "1+3" or "2+4" combo (which is usually present on 99% of modern motherboards, that's why they paint them memory slots in different colors, btw), rather your motherboard supports it by "1+2" or "3+4" combo, or doesn't have Dual Channel support at all (which is highly unlikely to find these days, because that would be stupid).
If you have a very big CPU cooler (something like NH-D14, I presume?), try installing your memory in the two blue slots ("3" & "4"), I think it would work just fine at full performance rate.
Your motherboard have two black slots in a row ("1" & "2"), and two blue slots in a row ("3" & "4"), so I think what they did, is that way so your Dual Channel accessed by putting memory close together, or (probably not, but...who knows?) it's accessed by putting memory planks in the very center, making a "2+3" combo...which would be waaay too strange, IMHO.