I have a Windows Server 2008 system, which has 12GB of RAM.

If I list all processes in the Task Manager, and SUM() the memory of each process (Working Set, Memory (Private Working Set), Commit Size, ...), I never reach more than 4-5GB that should be "in use". However, task manager reports this server has 11GB in use via the "Performance" tab.

I'm failing in determining where all that used RAM is going. It doesn't seem to be system cache, but I can not be sure.

It might be a memory leak in one of the appliances, but I'm struggling to find out which one. The server's memory keeps filing up, and eventually forces us to reboot the device to clear it.

I've been reading up on how RAM assignments work on Windows Server:

• RAM, Virtual Memory, Pagefile and all that stuff: http://support.microsoft.com/kb/2267427
• What's the best way to measure? http://www.zdnet.com/blog/bott/windows-7-memory-usage-whats-the-best-way-to-measure/1786
• Configure the file system cache in Windows: http://smallvoid.com/article/winnt-system-cache.html

But I fear I'm stuck without ideas at the moment.