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In the Windows Task Manager I have never seen the memory usage close to 100%. If physical memory is never depleted, how come computers have virtual memory? I realize many years ago maybe computers did run out of physical memory but I have never seen (according to the task manager) more than 80% of the machine's memory used.

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Which version of windows and how much memory do you have installed? – G Koe Apr 2 '13 at 4:28
I'm using Windows 7, have 8GB of memory, and am running a ton of programs at once. – Celeritas Apr 2 '13 at 4:31
Virtual memory? You mean the pagefile? – Havenard Apr 2 '13 at 4:37
@Havenard sorry but please speak with full sentences. I don't understand "virtual memory?". Thanks – Celeritas Apr 2 '13 at 4:43
@Celeritas - Virtual Memory is a well documented term. If you want to know more about that particular term there are hundreds of resources you can use to research that subject. Havenard's question actually is a complete sentence. The general purpose of virtual memory allows every application to use all the memory it wants and allows the operating system to manage this process. The reason virtual memory exists is because looking something up in memory isn't a free operation ( cost in performance ) – Ramhound Apr 2 '13 at 11:44
up vote 1 down vote accepted

The paging file is always enabled by default in every installation of Windows, are you going to use it or not. It doesn't avaliate the physical memory you have to decide that.

Microsoft recommends this is left enabled for reasons beyond my understanding, but if you want to disable it you can.

  1. Right click your Computer icon, click Properties;
  2. In the tab Advanced, click the button "Settings..." under Performance;
  3. Once in the Performance Options, go to the tab Advanced and click the button "Change..." under Virtual Memory;
  4. Uncheck "Automatically manage paging file size for all drives";
  5. Select any drive with paging file enabled and chose "No paging file".
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The page file is not only used when physical RAM runs out, but also as a guarantee that the memory is available IF needed.

Imagine a computer with 2GB free RAM, running an application requesting 3GB while only using a fraction of that. Without virtual memory, the OS would have to fail that allocation (and probably crash the program) as it would not be able to guarantee that all of those 3GB could end up being used.

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