16 GB of RAM truly necessary?

Hi everybody - I was simply wondering if 16 GB of RAM was truly necessary for VR. My current setup includes an Intel Xeon E3-1241 V3 (@ 3.5 ghz), GTX 970 Strix, and 8GB DDR3-2400 Memory. I plan on eventually upgrading, but as of right now it seems that wont happen until after I get the Vive.

E: thanks for all the replies everybody