Windows® Internals, Sixth Edition, Part 2

Physical Memory Limits

Now that you’ve learned how Windows keeps track of physical memory, we’ll describe how much of it Windows can actually support. Because most systems access more code and data than can fit in physical memory as they run, physical memory is in essence a window into the code and data used over time. The amount of memory can therefore affect performance, because when data or code that a process or the operating system needs is not present, the memory manager must bring it in from disk or remote storage.

Besides affecting performance, the amount of physical memory impacts other resource limits. For example, the amount of nonpaged pool, operating system buffers backed by physical memory, is obviously constrained by physical memory. ...