Unused RAM is wasted RAM. In other words, if we were able to have 50% free memory at all times, why not reduce the amount of memory in the PC and lower its cost?
This area is well discussed. Windows should use as much RAM as possible, even if for a trivial reason.
I just bought NP530U3C with i3, Intel HD 4000 and 4 gigs of RAM. Everything is ok, but when I start system grabs 56% of RAM (Win 8). Is it normal even after I've deleted all of unnecessary apps that come bundled with my ultrabook?