Is that a PC with more than one CPU or more than 64 threads?
Happening on a machine with 2 x CPUs, 48 threads in total (2 x 12-core + HT), 64GB RAM and basically the same again but the other machine is 2 x 10-core + HT. It's interesting.. .watching a render start the physical ram usage is around 30GB or so, but then the available RAM amount drops to nearly 0, which tells me it's using the page file I guess...