The next time you log on to your PC, check out your system settings under the Windows Control Panel. Notice how there are two different memory readings? Windows displays both the "installed" and "usable" RAM, allowing users to see exactly how much memory their PC is utilizing. So, what’s the difference between installed and usable memory?
You will typically see a slightly lower amount of usable memory than what is actually installed in your PC. This is completely normal and should not be a cause for concern. For example, if you have 6 GB of RAM installed, Windows may show 5.46 GB of usable RAM. This small difference is due to what is known as "hardware reserved" memory. Certain computer components, such as video/graphics cards, use hardware reserved memory, thereby reducing the actual usable RAM.
Factors Affecting Usable Memory
According to Microsoft, the difference between installed and usable RAM depends on the following factors:
- The hardware installed in the computer and its respective hardware reserved memory usage.
- The motherboard’s ability to read and handle memory.
- The system BIOS.
- The version of Windows.
In some cases, the operating system may limit a computer’s total amount of usable memory. For example, 32-bit versions of Windows are generally unable to use more than 3.12 gigabytes (GB). Regardless of how much memory is installed, the system will only read a maximum of 3.12 GB as usable. However, 64-bit versions of Windows can utilize significantly more memory.
When the Difference is Too Large
In certain cases, the difference between installed and usable RAM is unusually large. Returning to the example above, a PC with 6 GB of installed memory should not show only 2 or 3 GB of usable memory. This is a clear indication of an underlying problem, and failing to address it could result in significantly reduced performance.
How to Increase Usable Memory
The first step to increasing your computer’s usable memory is to remove the RAM sticks and reseat them in their slots. Reinstalling the memory is often a quick fix for this issue.
If that does not work, check your Windows settings to determine if a maximum memory limit is specified. In Windows 7, follow these steps:
- Click Start > type msconfig > select Advanced options > and uncheck the "Maximum memory" option.
BIOS Issues
As mentioned earlier, the system BIOS may also be a cause of lower-than-expected usable memory. If you have an older computer, check online for a BIOS update. Most BIOS manufacturers provide download links to the latest versions of their firmware.
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