Set the max degree of parallelism option for optimal performance
Applies to: 
SQL Server
This rule determines whether the max degree of parallelism (MAXDOP) option for a value greater than 8. Setting this option to a larger value often causes unwanted resource consumption and performance degradation.
Best practice recommendations
The max degree of parallelism (MAXDOP) configuration option controls the number of processors that are used for the execution of a query in a parallel plan. This option determines the number of threads that are used for the query plan operators that perform the work in parallel. Depending on whether SQL Server is set up on a symmetric multiprocessing (SMP) computer, a non-uniform memory access (NUMA) computer, or simultaneous multithreading (SMT) enabled processors, you have to configure the max degree of parallelism option appropriately.
Recommendations to configure MAXDOP depend on the version of SQL Server being used. For version specific guidelines, see Configure the max degree of parallelism Server Configuration Option, and configure the policy to verify the value of max degree of parallelism accordingly.