[ The PC Guide | The PC Buyer's Guide | Designing and Specifying PC Systems and Components | Key Performance Issues In PC System Design ]

One of the biggest problems with the way many people consider performance is that they treat it as a single entity. In fact, there are many different aspects and factors involved in overall PC performance. There is no single number that can properly express the performance of a PC system, and anyone that tries to tell you otherwise is "selling something". Many hardware manufacturers are guilty of this, especially CPU makers that want people to focus far too much attention on the speed of the system processor.

There are several key components that are most important in terms of their influence on the overall performance of the typical PC. These are the CPU (system processor), system memory, video card, and hard disk drive. How important each of these is relative to the others depends entirely on how the system is being used. In some systems and for some applications there are other components that are as important to overall performance or possibly even more important than those four.

Here are some sample applications or uses of PCs and a brief discussion of what the performance priorities typically are for them:

• Gaming System: CPU and video performance are by far the most important. Adequate memory is necessary but only to a point. Storage performance is not that important in most cases. Communications requires attention if playing games over a network or the Internet.
• Graphics Workstation: Memory, video, CPU and hard disk storage performance all matter, probably in that order. The amount of memory is in many ways more important than the specific type. Some applications require more frequent file loading and saving; for these, hard disk performance probably moves up the priority list.
• Multi-User File Server: Memory and hard disk storage are most important; CPU performance slightly less so but also requires attention. Video performance is irrelevant; many servers have very cheap video cards as they are not generally used except for administration of the server.
• Internet Use: None of the components I mentioned are particularly critical for Internet use: the Internet connection is. Even the slowest CPU sold in modern machines will spend 99.99% of its time sitting around waiting for an analog 28.8K modem. Upgrading the connection to a 56K modem or faster connection will result in far greater improvements than anything else you can do with the hardware.
• Multimedia (Audio and Video): Storage devices and system memory are very important, as is CPU speed. For video editing, the video subsystem is also important. For audio work the performance of CD or DVD drive in the system may be far more essential than any other component, and this can have an impact on the entire storage subsystem.
• General Home or Office Use: There are no particular areas where performance is terribly crucial. A balanced approach is best, and not much attention needs to be paid to performance specifically. However, the hard disk probably requires the most attention since it is the slowest component that directly affects overall performance.

Those are only a few examples, but they give you the general idea. When designing a PC, you have to decide which areas of performance are most important to you. How important the various factors are, and in fact the degree to which performance matters at all, depends entirely on how you use your system. Unless you have an unlimited budget, you will end up having to trade off performance in one area for performance in another, to some extent. At the same time, most PC users should watch out for a lack of balance in the key performance-related components and also in the capacity of the system; see here for more.

Tip: In the pages discussing selection tips for individual components, I describe the performance impact and importance of each component.

Next: The Dangers of "Magic Numbers"

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