Clear your ram cache with RAMMap's emptystandbylist option.
http://technet.microsoft.com/en-us/sysinternals/ff700229.aspx
Alternatively, wj32 (writer of Process Hacker at sourceforge) has written a small cmdline app to do the trick. Find it in this thread.
http://forum.sysinternals.com/rammap-empty-standby-list_topic27297.html
Have not found a way to do this from Powershell yet, but if you are a good programmer you can find what you need in the source code of Process Hacker.