opc.three (9/10/2012)
I think the OP is saying memory used by sqlservr.exe per Task Manager (count on Processes Tab should include buffer pool for x64 SQL) is only 124MB but Task Manager Performance Tab is reporting 7.5GB of the 8GB of physical memory is used. Further to that, the majority of the 7.5GB is unnaccounted for in the Processes Tab.I have seen this scenario reported before and the OP never got to the bottom of it: http://www.sqlservercentral.com/Forums/Topic1267628-146-1.aspx
He's running locked pages in memory and Task Manager does not report memory allocated using the physical alloc that SQL uses when locked pages is enabled.
Chapter 4: http://www.simple-talk.com/books/sql-books/troubleshooting-sql-server-a-guide-for-the-accidental-dba/, page 148
Task manager should never be used to check SQL's memory because it only shows memory allocated via VirtualAlloc, not AllocateUserPhysicalPages and hence gives completely incorrect results when locked pages is enabled (or AWE on 32-bit)
The reliable way to check SQL's memory usage is with the TotalServerMemory perfmon counter.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability