Small RAM upgrade question for Alienware Aurora R5

Hi! I currently have an Alienware Aurora R5 with 2 x 4GB 2133MHz RAM sticks and am really happy with it so far!

But I would like to add another 8GB 2133MHz stick to bring it up to 16GB, thing is, I'm not entirely sure if I can just slot another 8GB stick into the XMM3 slot and have it work,

partly because i couldnt find any documentation on what the voltages/timings/cas latency are on the 2 4gb ram sticks in the pc currently are, and I think those are important to upgrading ram,

And because of this thing i found in the online manual for the R5

Seems to say that there are only  5 configuration's I can have, is that set in stone or is it just what they've tested?

Thanks, Saucybagel

P.S. I moved it here instead of the "Desktop computer Forums (Audio, General Hardware, Video" as advised.

P.P.S. Well, Copied it over anyway, dont know if i can move posts, heh [^o)]