Wrong Memory is displaying in task manager for Default and Named instance in Sqlserver I have installed 2 instances on a Sqlserver 2016.When the Performance of the server is degrading ,  i could see huge transactions are happening on the Default instance and there were no connections and a single small database in a named instance.But when i see in the task manager , i see the memory of the named instance is increasing drastically with no CPU and default instance remains idle with High CPU.
Perhaps you have Lock Pages In Memory for the &quot;active but low memory&quot; instance? Task manager only show a minuscule memory usage in this case. You can for instance look in the error log file (startup info) if lock pages are used.
So, there's nothing to &quot;fix&quot;. You should look at the memory usage through something else then Task Manager. For instance sys.dm_os_process_memory (physical_memory_in_use_kb) or sys.dm_os_sys_info (committed_kb)