Discrepancy between memory in use reported by the task manager and memory used by programs

Question

My task manager

As you can see it displays I have 2.27 GB in use, over half of my physical memory (4 GB):

My list of processes

Processes are ordered by memory

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As you can see the total amount of memory used by processes is around 1.2 GB. So what's using all that memory?

What's really annoying is that it doesn't seem to be used by cache or similar. If I need to allocate that memory, it won't automagically become available: it will start swapping, and everything starts to be incredibly slow.

What's that memory doing?

Answer 1

It's probably "SuperFetch"(see good posts here,here,here) that's caching memory.
A quote:

...And this brings us to the question of what to do with RAM. I have 4GB of main memory in my main desktop machine, and I would find it a total waste if the operating system did not use it to make my computing experience smoother. Isn't that why I got 4GB of top-quality RAM in the first place? To make my machine faster?

This is exactly what SuperFetch does. It's an intelligent mechanism that uses the RAM in a machine to its fullest potential to make computing a smoother experience....

UPDATE
Also, give RAMMap a try. It'll show you a whole lot about how memory is allocated in your system.

Answer 2

The list of processes doesn't show a number of things:

• the system files (*.dll, *.kbd, etc.) that are loaded and needed to run Windows.

• the file cache.

• the "Modified" part of the memory (See Resource Monitor).

All these thing put together + all programs/processes running occupy (in your case) ~ 2.27 GB (See the tab "Performance" in Task Manager). If you want reduce memory usage then you should install a program called CLEANMEM.

Disabling "SuperFetch" doesn't help because it manages the caching in the "Standby" part of the memory (Resource Monitor) and Superfetch doesn't manage the "In Use" & "Modified" part of the memory (Resource Monitor).

Answer 3

On the Vista and Win 7 Task Manager display shown, the "cached" counter includes both the traditional file system cache (the "reactive" cache), and the Standby page list. The Standby page list is also part of the "Available" counter. A subset of the Standby page list is likely being used by Superfetch (unless you've disabled that).

Everything that's on the Standby page list - even if it's used by Superfetch - is indeed "available" for immediate use by a process that needs RAM. But the stuff in the reactive file cache is not. There is no process for that, so it doesn't show in Task Manager's processes list.