Installed vs Usable Memory: What’s The Difference?

The next time you log on your PC, check out your system settings under the Windows control panel. Notice how there’s two different memory readings here? Windows reads 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’ll typically see a slightly lower amount of usable memory than what’s actually installed in your PC. This is completely normal and shouldn’t cause any reason for concern. If you have 6 GB RAM installed, Windows may read 5.46 GB of usable RAM. This subtle difference is the result of what’s known as “hardware reserved” memory. Certain computer components like video/graphics cards use hardware reserved; thus, lowering the actual usable RAM.

According to Microsoft, differences between installed and usable RAM depend on the following:

· Hardware installed in the computer and its respective hardware reserved memory usable.
· Motherboard’s ability to read and handle memory.
· System BIOS.
· Windows version.

In some cases, the operating system may limit a computer’s total amount of usable memory. 32-bit versions of Windows, for instance, are generally unable to use more than 3.12 gigabytes (GB). Regardless of how much memory your computer has, it will only read a maximum of 3.12 GB usable. 64-bit versions of Windows, on the other hand, can use well beyond 3.12 GB memory.

But there are some cases in which the difference between installed and usable RAM is unusually large. Going back to the example mentioned above, a PC with 6GB installed memory shouldn’t read 2 or 3GB of usable memory. This is a tall-tale sign of an underlying problem, and failing to address it could mean significantly lower performance.

The first step you should take to increase your computer’s usable memory is to remove the RAM sticks and place them back into the slot. Shuffling the memory around is often a quick fix for this problem. If that didn’t work, check your Windows settings to determine whether or not there’s a maximum memory specified. For Windows 7, this is done by clicking Start > type msconfig > Advanced options > and click to remove the “Maximum memory” option.

As previously stated, system BIOS may also cause a lower than expected usable memory. If you own an older computer, search for the new BIOS online. Most BIOS manufacturers offer download links to the latest versions of their products online.