Quote - Yep.  Why the addressing is limited like this is a mystery.  You'd think that just by virtue of updated OS process allowances, Poser would be able to access the full 32-bit range given by Windows or MacOS. Is there somehow some built-in check to avoid using more memory than a certain amount?

Nope, no built-in checks. Poser is using standard malloc+free/new+delete for memory handling. And I have seen it go up to 2.5GB VRAM usage on OS X (haven't tested on XP in a long time). If it bails out earlier, it means that a memory request has been rejected by the OS.