Adding ram to poweredge r710

Hello,

I want to add additional RAM to my Dell Power-edge r710 dual cpu rack-mount server, but am not sure of the best approach. The server is currently in optimizer mode and has a 2gb in A1,A4,A2,A5,A3,A6,B6,B3,B5,B2,B4,B1. I would like to add another 16gb of memory, I do have a single 16gb stick available if it's possible to use. If not I wanted to know the best approach to upgrade.

Thanks!