CPU interference with 384GB DDR4 RAM?

Looking at used listings, Xeon Workstations with, or at least upgradeable to, 384GB DDR4 RAM, are increasingly affordable. If my only concern is to be able to run as good a model as possible, without much concern for t/s (as long as we're not talking seconds per token), what is realistically possible in terms of CPU with such a system and can I take full advantage of this amount of RAM?