This is mine and I could care less what it is showing. If the computer is working fine I don't worry about the small stuff. Now if it was showing only 1/2 of it than I would looking at some thing.
Now I have other computers and it shows 16gb. With 16gb installed why does windows do this I don't. I don't run page file memory on any computer with 8gb or more. You don't need it.
Maybe you would think that could be it, but I do the same thing with the other computers too. absic is right it is a windows thing. If you do figure it out just let us know.