I do have matched pairs of Ram.
As for Cinema 4d, I did a deeper look, and with the current 32 bit version, only 4gb of Ram can be used. They are working on the 64 bit version which can support more.
The object that I used in the scene had a lot of detail for a close shot, but then I used it in another scene so it did have too much polys for my machine to handle. I turned down the hypernurbs amount to 2 in editor and 3 in renderer. That solved it for me.