The missing ram is probably one of two things. Either one of the slots on the board is broken (easy fix, just use the other colored set of slots), or one of the sticks of ram is bad. Shouldn't be too bad to figure out if you decide to look into it.
Both of those are possibilities. I used this combo as a server and realized I didn't need as much computing power after the fact. Would make for a really good server too. As I've seen others mention, if you drop an octacore Xeon into this board it can go toe to toe with an X79 setup too, but for quite a bit cheaper.