What Determines Computer Speed?
Great computer performance can be desirable for fun, practicality or both. If you are a photographer working with the new 20+ megapixel cameras, an investor processing large data sets, someone working with large amounts of scanned documents or a person or business which would benefit from faster computing, knowing how to choose a fast computer can be the root of superior productivity and enjoyment.
It is the combination of characteristics that enables fast computing. There is no single component that can be thought of as "the component" that is responsible for computer performance. Companies that are dependent on repeat and redundant purchases promote computer disposability by focussing on one or two components (usually CPU and RAM) as the primary components responsible for computer performance. This is actually incorrect. Companies that focus on these components do so because these are the fastest changing components. By making these the concern of consumers, they are able to sell replacement computers to a single consumer every one to two years, when that consumer could have had a better computer that would have remained fully functional for a minimum of seven to ten years.
A computer system is the combination of various independent components connected to each other. It is the combination of various characteristics that creates the fastest computer system. This article focusses on the performance of "client" (non-server) computers.
The first thing to understand is that the system will only be as fast as the slowest component being used. Though there are parts of the computer that are only used sporadically, there is one component that used almost all of the time and this component also happens to be the slowest of all of the components: the hard disk drive. The hard disk drive is the component that is the most important consideration when thinking about a fast computer. Hard drive performance is determined mainly by interface type and access time. Interface type is the method used by the hard drive to interface with the host computer. The fastest of all interface types is U320 SCSI. This interface is special because it allows the drive to process certain information without using resources of the host computer. The second fastest option is a lower cost version of SCSI called SAS. SAS may someday be faster that U320 SCSI, but currently it is slightly slower. Avoid SATA and PATA interfaces. Once you have narrowed your computer selection to a group that uses U320 SCSI hard drives, the next thing to consider is access time (aka seek time). Stated simply, this is the average duration needed for the hard drive to find information on its disks. Look for 3.5ms or lower.
After you've narrowed your search to computers with fast hard drives, the next important characteristic is the platform. In the next article the difference between PCs and Workstations will be discussed: specifically the characteristics that lead to the fastest configurations.