What's the maximal supported RAM capacity in the editor?

We have a game that focuses heavily on detailed and photorealistic asthetics, so when I tried to bake my lightmap, only for a "small" level, it totally overused my RAM. So I thought of upgrading my RAM capacities, but is it worth it? currently I am using a single 16gb-ddr4 platine.... my mainboard's maximal capacity is 256gb! :O How much would you suggest, or can unity / w7 even handle?

Thanks in advance and best wishes, Kay b 14