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CPU Speed

Since the system processor (CPU) is involved in everything that happens in the PC, it of course has an impact on hard disk performance. However, this impact isn't nearly as great as you might think. The reason is that the CPU is so much faster than anything related to the hard disk, particularly today, that it normally spends a great deal of time waiting for the hard disk. There's virtually no way for the CPU to really affect the performance of the storage subsystem all that much if the hard disk and system are properly set up. On older systems though, the performance of the CPU was sometimes a real factor in hard disk performance. And even today, if an interface mode is used that results in high CPU utilization by the hard disk interface, overall performance can become somewhat dependent on the performance level of the CPU itself.

The real issues with CPUs and hard disks are related to benchmarks. Every benchmark that you run on your hard disk involves instructions that are processed on the main system CPU. A faster CPU will run these benchmarks faster than a slower one, and I have found it to be quite consistent that testing the same drive on a machine with a much faster CPU, will result in higher scores. This is accentuated when using one of the transfer modes that requires intervention from the processor, such as programmed I/O.

Next: Interface Bus Speed

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