Usable memory is the amount of the total physical memory minus hardware-reserved memory. It is normal for the operating system to report slightly less usable memory compared to installed memory, as in the following example.
Hardware-reserved memory is expected and can be affected by several factors:
- Devices installed in the computer, and the memory that is reserved by those devices
- System BIOS version and settings
- Operating system version that is installed
- Other system settings
If your system shows that there is much less usable memory than expected, less than 3 GB, try updating the system BIOS to the latest version available on Download Center.