How to: Configure the Number of Processors Available for Parallel Queries (SQL Server Management Studio)
Use the max degree of parallelism server configuration option to limit the number of processors (up to a maximum of 64) to use in parallel plan execution.
In Object Explorer, right-click a server and select Properties.
Click the Advanced node.
In the Max Degree of Parallelism box, select the maximum number of processors to use in parallel plan execution.
The default value of 0 uses all available processors. Set max degree of parallelism to 1 to suppress parallel plan generation. Set the value to a number greater than 1 to restrict the maximum number of processors used by a single parallel query execution. If a value greater than the number of available processors is specified, the actual number of available processors is used. If the computer has only one processor, the max degree of parallelism value is ignored.