RAM does not matter. Poser is restricted to 4GB address space as any 32 bit application, so only the 64 bit firefly of Poser Pro is able to access more memory. And that virtual memory can come from RAM or swap file. Even a PC with only 512 MB RAM can render a Poser scene that uses 1.5 GB of memory.

Poser can use up to 2/3 GB on 32 bit Windows and 4GB on 64 bit Windows. So more RAM won't help you anything - for rendering only if you got Poser Pro.