> What I am seeing is that in Task Manager, sqlserver.exe is using about 163 Mb of RAM, if I use procexp, the same service shows just under 500 MB of RAM used. 

You should never look at task manager or *some other relevant tools* to check SQL Server memory utilization. They would never yield correct results. You should use a DMV [sys.dm_os_process_memory][1], if you are using SQL Server 2008 and above, to check SQL Server memory utilization.

    select 
    (physical_memory_in_use_kb/1024) as PhyMemory_usedby_Sqlserver_MB, 
    (locked_page_allocations_kb/1024 ) as Locked_pages_used_Sqlserver_MB, 
    (virtual_address_space_committed_kb/1024 ) as Total_MemoryUsed_in_MB, 
    process_physical_memory_low, 
    process_virtual_memory_low 
    from sys. dm_os_process_memory

**Note:**

`PhyMemory_usedby_Sqlserver_MB` is the committed memory and is backed by physical RAM.

`Total_MemoryUsed_in_MB` is the **total** memory used by SQL Server (RAM and page file)
 
You are doing mistake, which probably many 'newbies' do when referring to memory utilized by SQL Server. SQL Server would never show you correct memory utilization in task manager if [Locked pages in memory privilege(LPIM)][2] is there for account running SQL Server service because task manager only shows Process Private Bytes, the memory allocated via [Virtual_alloc function][3] which is pageable. Now if SQL server service account has LPIM most part of memory allocation would be done by [AWE API][4] and this allocated memory is NON pageable and thus does not comes under task manager,in the end showing you different values. Hope this is clear

Other point to note is task manager shows memory utilized by all OS processes so why are you even referring to it and making wrong conclusion about SQL Server. Remember Task manager is Windows tool not a SQL Server tool.


  [1]: https://msdn.microsoft.com/en-us/library/bb510747.aspx?f=255&MSPPError=-2147217396
  [2]: http://blogs.technet.com/b/askperf/archive/2008/03/25/lock-pages-in-memory-do-you-really-need-it.aspx
  [3]: https://msdn.microsoft.com/en-us/library/aa908768.aspx
  [4]: https://msdn.microsoft.com/en-us/library/windows/desktop/aa366527%28v=vs.85%29.aspx