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What is the difference between physical memory and available memory?

Answer: Physical memory is how much RAM you have installed in your computer. For example, if you have two 512 MB memory chips in your machine, you have a total of 1 GB of physical memory. This memory is what your computer uses to load the operating system as well as individual programs and files.

Available memory refers to how much RAM is not already being used by the computer. Because loading the operating system takes up memory, your available memory drops right after your computer boots up. You can reduce how much memory the operating system uses by uninstalling system files or extensions that are often installed by utility programs.

Each time you open a program, it is loaded into your computer's memory, and therefore reduces your available memory. Large programs such as Adobe Photoshop and 3D action games take up more memory than simple programs like text editors or spreadsheet programs. If you need more available memory to open a large program, you should first quit other programs that are running.

The best way to increase available memory is to add more RAM, or physical memory, to your computer. Before doing this, make sure your computer has open memory slots. Some utility programs claim to "double your RAM," but they often slow down your computer signficantly in the process. Adding more physical memory to your computer gives your applications more breathing room and therefore should help your computer run faster.

Published: February 23, 2005 — by Per Christensson

Answer from the PC Help Center