So I pulled up my Task Manager today, and found that out of my 16GB of RAM, 14.5GB was "in-use".
Naturally, I switch to the Processes tab, click "show processes by all users", and sort by Working Set - only to find that all the processes listed in Task Manager together only use up ~3GB of RAM. I've also tried Process Explorer, which doesn't give me any new information.
So what's eating up almost 11GB of RAM?
I found one tool - RAMMap - which tells me that 11GB of ram is being used by "Paged Pool". What is this used for? And how can I find out what caused it to spike up so high and stay high?