I don't think it's healthy to think of that 4GB module as "RAM".

It's connected to your CPU by a serial communications interface so access is not uniform or timely, and if the CPU needs any of it, it stops what it's doing while it waits.

The "cache ram" (L1 and to a lesser extent L2) actually acts like the RAM that we learn about in Knuth, so that when we discuss algorithms in terms of memory/time costs, this is the number we should be thinking about. Algorithms that are performant on disk/drum are modern solutions for what you're calling "RAM".