NAV 2013 R2 Performance on SQL Server 2012

Dear Sir,

The SQL Server is running on a well  configured Server. The Server Configuration is given below.

1. OS - Windows Server 2012 R2
2. RAM - DDR3 24 GB ECC
3. RAID 10

The NAV SERVER is also installed in the same server. Almost 112 concurrent End-users are accessing the NAVISION Database thru different clients system.

I have noticed that in a particular time( 5PM/6PM) the SQL as well as the NAV SERVER are consuming the whole (20GB+) RAM of the Server everybody & makes the Server unstable.

So, please let me know how to solve this issue.


Thanks in adv.