Good question. The 7-series southbridge supports 4 SATA connectors natively. That board according to Newegg has 2 additional RAID controllers on board, but it doesn't list what they do. I want to say that the black ones are definately connected to the Intel Southbridge, One of those might be designed to be connected to an external Sata connector (I think you kinda described it),and maybe the other two tied to another chip? Doesn't make sense...and I couldn't find the answer exactly for you just peeking around.