How to free used memory in Windows Server 2008 R2

memorymemory usagemonitoringtask-managerwindows-server-2008

The Task Manager and the Resource Monitor say that the memory is 95% used, but the sum of the memory used by the listed processes don't sum up to 20%. Where this 75% of usage is coming from? How to free it?

Edit: It was probably a memory leak, solved with a reboot. Is this the only solution to a memory leak?

Best Answer

This may be a memory leak from an application. What happens after a reboot? A slow return to 95%?