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CPU clock speed is the number of cycles a CPU performs per second. Clock speed is measured in gigahertz (GHz). A higher clock speed indicates a faster CPU. For example, a clock speed of 2.1 GHz equals 2.1 billion cycles per second and a 3.6 GHz CPU can perform 3.6 billion cycles per second. Within the same generation of processors, if the number of cores and CPU cache size is the same, the higher clock speed clock CPU will outperform the other processor.
Processors have a base clock speed and a boost clock speed. The base clock speed is the default frequency of the CPU. The base clock speed should be the first consideration when reviewing the processor frequency of a CPU. This is because the CPU will not operate at a lower processor frequency than the base clock speed unless the server BIOS and operating system have power-saving enabled.
The boost clock frequency is the capability of a single CPU core to increase the processor frequency in the event of an intense workload. Enabling boost clock frequency increases processor performance by processing more instructions per cycle. When processor performance increases, the processer uses more power and creates heat. This means that the boost clock frequency depends on thermal headroom and power regulation to function. Modern CPUs can boost clock speed of individual cores which balances the burst in workload with the heat generated by the increased frequency.
CPUs only use boost clock frequencies during peak workloads for the individual CPU core. Running boost clock speeds all the time causes challenges due to the excessive heat generated, power consumption, and possible risk of CPU failure. CPU cores return to the base clock speed if the peak workload completes or if heat becomes excessive.
Most enterprise applications are multi-tier architectures. Some part of the architecture might benefit from higher clock speeds, as the applications are single threaded. Higher clock speed CPUs can process single threaded applications faster than large multi-core systems with lower clock speeds.