Step 10: Optimize CPU activity and speed
Number of CPUs
Most SQL Server operations take advantage of multiple processors, but you have to determine how much spillover goes to the second or subsequent processors. For most workloads, Task Manager will reveal that CPU activity occurs on the first processor with little on the second processor and even less on the third and fourth. If at all possible, study a representative workload to see how many processors you must have to satisfy needs. You can save on the per-processor licensing costs by using fewer processors, and then add them using the affinity switch as your workload increases.
In general, most complex SQL Server operations (i.e., joins, aggregate operations, etc.) are processor intensive, and performance will improve on higher CPU systems. Study the processor queue length to determine if CPU is a bottleneck. If the queue length will consistently be above 2, you should consider using additional or faster processors.
L2/L3 cache is temporary processor storage used by the microprocessor. For processor-intensive workloads, select the largest L2/L3 cache available. Currently, the largest cache on Xeon processors is 1 MB. The new Itanium processors have an L1, L2 and L3 cache -- the largest L3 cache is 9 MB.