SE is a 32 bit program. (Probably the other programs too.) 32-bit programs can only address 4 gigabytes of ram. Therefore you can have as much memory as you want, it does not help you.
However, these programs should not use up this memory. They should either release the memory dynamically or at least issue a warning that they are approaching this limit.
JackDole's Universe: http://forum.spaceengine.org/viewtopic.php?f=3&t=71
JackDole's Archive: http://forum.spaceengine.org/viewtopic.php?f=3&t=419
JackDole: Mega structures ... http://old.spaceengine.org/forum/17-3252-1 (Old forum)