Super User is a question and answer site for computer enthusiasts and power users. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I am running some tests on a very powerful machine ( 24GB RAM, Window 2008 64bit )

I checked my task manager: Physical memory: 98% ( RAM is 24GB )

But the totally "Memory(Private working set)" usage of all my running processors is no more than 16GB

Where are those extra 8GB used for? Is it used by the OS IO buffer, or somewhere else?

Can anyone contribute some ideas?

share|improve this question
"Windows memory management is rocket science. And don’t believe anyone who tells you otherwise."… – Moab Nov 19 '10 at 19:44

Yes, used for caching and buffers. Modern OS's try to be smart...if you have 8GB of memory just sitting idle, not being used for anything, it's being wasted. So as long as no application is requesting it, the OS finds other things to use it for to try and speed stuff up. Don't worry about it -- if you application needs the memory, the OS will instantly free it up as soon as the app asks for it.

share|improve this answer
This is also why things will be paged to disk even if the RAM isn't full; so that if the system needs to free up the RAM it can do so immediately. (This is why it's always a bad idea to turn your paging file off.) – Shinrai Nov 19 '10 at 20:30

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .