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The CPU is the brain of the computer. Although the processor isn’t the only component that affects overall system performance, it’s the one that most people think of first when deciding what type of server to purchase. At the time of this writing, most servers used one of several variations of Intel’s Xeon processor. These processors are designed specifically for server computers rather than client computers, and offer from 4 to 22 independent processor cores, depending on the model.

Each motherboard is designed to support a particular type of processor. CPUs come in two basic mounting styles: slot or socket. However, you can choose from several types of slots and sockets, so you have to make sure that the motherboard supports the specific slot or socket style used by the CPU. Some server motherboards have two or more slots or sockets to hold two or more CPUs.

Clock speed refers to how fast the basic clock that drives the processor’s operation ticks. In theory, the faster the clock speed, the faster the processor. However, clock speed alone is reliable only for comparing processors within the same family. What matters more in a server is the number of processor cores. The more cores the server has, the more tasks the server can perform simultaneously. Since servers are in the business of supporting many clients, being able to do many tasks simultaneously is a huge benefit for server performance.

What’s more, processor cores utilize a technology called hyperthreading, which effectively lets each processor core juggle two threads at once. (In general terms, a thread is a sequence of instructions that performs a single task.) Because each core can handle two simultaneous threads, a processor with four cores can handle eight concurrent threads.

Many server motherboards can support two separate processors, which doubles the potential workload of the server. For example, if the server has two 14-core processors, the server has a total of 28 cores available for its workload. Because of hyperthreading, each of these 28 cores can handle 2 threads, so the server can handle 56 concurrent threads.