Download
Process explorer and run it as admin (it comes from Microsoft so its safe)
the default view is tree structure meaning like your task manager screen, it will show what processes are under each service, but unlike task manager, it shows the ram usage of each part so you can see what is eating your ram
Private bytes = actual ram usage
Working set = Ram + page file usage
This page shows what all the colours and headings mean, link at bottom of it shows how to use it to find problems. You can right click headers and run an av scan from within the program.
you might have a memory leak in a driver
I was going to blame previously closed programs but you only have 232mb compressed so its not that.
What does it look like if you close Chrome as its using a lot there - sort resource monitor by private bytes as that is actual ram usage