Hi, I just received my stock 5K iMac with Intel i5. I also just ordered, based on reading these forums, the following RAM: "Crucial Ballistix Sport SODIMM 16GB Kit (8GBx2) DDR3 1866 MT/s (PC3-14900) CL10 @1.35V 204-Pin Memory BLS2K8G3N18AES4" My question is twofold: 1) Is 16 GB @ 1866 Mhz enough to smoothly run a moderately intensive Yosemite? 2) Will I be able to add an additional 16 GB of the same RAM in the future, if need be? (Total RAM would in that case be 32 GB). Thank you, and apologies if this has been answered before.