is it noticeably affecting your PC or you just wondering where all your ram is?
task manager just shows your usage, not total system usage. There are more system controller users that could be doing things in background to carry out the tasks you want done
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 = Ram + page file usage
Working set = actual ram 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.