Stop looking at your RAM usage.
If your computer has RAM available, the point is for the computer to USE said RAM. If the RAM is unused, it means that when you need to access data, the computer will have to access the HDD and load it, which is super slow, vs reading it straight from RAM. You'll want the computer to pre-load things based on your usage patterns.
Look up Windows and super-fetch and pre-caching and all the technologies related to it.
Now, if you have an actual problem, then list the actual problem, like, "I need to do this thing that uses lots of RAM, but computer crashes."
Your system monitor is giving you a useless piece of information (RAM usage), and you're trying to fix a "problem" that is non-existent.