Ever noticed SQL using most of the Memory (RAM) on the server and all your other applications start slowing down? This could be because SQL is using the maximum amount of memory it can get a hold of.
When SQL is installed the default max amount of memory it is allowed to use is set to 2147483647 MB. You can check this by right-clicking on the server at the top in the Object Explorer, selecting Properties, then selecting memory.
To decide what to set the max memory of SQL to use you can use this simple rule; leave 4GB or 10% of total memory free, whichever is larger on your instance to start with, and adjust this as needed. The free memory will be consumed by the OS and other applications on the server.
To calculate this, remember 1GB is 1024MB. If your server has 32GB of RAM then you would take 28 x 1024 = 28672MB. You would then insert this into the max memory.
NB! This does not require restarting your SQL Server instance, but it will cause execution plans to recompile.