replace.me › en-us › topic › the-usable-memory-may-be-less-th. For example, a bit version of Windows 7 may report that there is only GB of usable system memory on a computer that has 4 GB of memory installed.
Right-click any part of the Header , then click " select items " to add it in. If 4 GB of system memory is already installed, part of that address space must be reserved by the graphics memory mapping. The main question remains that where are the other part of memory gone?