Originally Posted By: Dignan
That's what was confusing me. I can't imagine how you're running out of ~3.5GB of RAM when you're not even using the computer. At the very least, I'd imagine that a decent backup program would give you the option to use fewer system resources.

You've got the memory and nobody is using it so the OS might as well use it to cache files. If an application does need that memory then it'll get released and allocated.