Weird memory usage in Windows Server 2008 R2
Is this a 64bit server - do you have the lock pages in memory local policy enabled? SQL is likely consuming the rest of your memory If you look at the perfmon counters you will see the memory allocation
Here is an article that explains it in depth
You can also view the counters in SQL
SELECT object_name ,Counter_name ,cntr_value ,ROUND(( cntr_value * 8192.0 ) / 1048576, 0) AS cntr_value_MB FROM sys.dm_os_performance_counters WHERE object_Name LIKE '%Buffer Manager%' AND RTRIM(counter_name) IN ( 'Free pages', 'Total pages', 'Database pages' ) UNION SELECT object_name ,Counter_name ,cntr_value ,ROUND(( cntr_value / 1024 ), 0) AS cntr_value_MB FROM sys.dm_os_performance_counters WHERE counter_name IN ( 'Target Server Memory (KB)', 'Total Server Memory (KB)' )
Quick test: restart SQL Server.
Another quick test: restart IIS.
You'll know for sure if one of them is the culprit, or if you have to look somewhere else.
It may help to use RamMap to see where your memory goes to.