The Computer Case

Chassis– a plastic or metal frame that holds and protects your computer parts.

There are two basic types for chassis

· Tower Case – it is designed to stand vertically that will lessen the space being occupied. It comes in three basic sizes: full, midi and mini.

· Desktop Case – it is designed horizontally which are usually used for office or home PCs. It comes in two basic sizes: standard and slimline.

To casual users, the PC is a metal container, attached by a few cables to a keyboard, mouse, and monitor. In fact, the case is more than just a box to house a computer. The real value of a case does not lie in the label, color, or how pretty it looks. Instead, the case houses all the internal components, offers access to the outside world via ports and connectors, and protects the PC's delicate circuits from damage and electromagnetic interference (EMI). It also protects surrounding devices, such as TVs, from the PC's EMI.

NOTE

Electromagnetic interference (EMI) is a newer term for radio frequency interference (RFI). EMI is any radio frequency that is emitted from an electrical or electronic device that is harmful to the surrounding equipment or that interferes with the operation of another electrical or electronic device. A computer interferes with radio, telephone, or TV reception when it generates EMI. Any high-quality computer will contain special circuits and grounding to prevent emissions from escaping into the surrounding area. Running a computer without its cover is a sure way to generate EMI. The case design is also often used to underscore the identity of a specific brand of computer, and can often be part of the reason we purchase a particular computer. Some people will also choose a case design for its appearance. We do, after all, want something that looks good, especially if we are spending a lot of money on it. With some cases, however, there may be a more technical reason for the case choice, such as the number of drive bays available.

Early computer cases were little more than boxes that sat on the desk and served as monitor stands. Today, some manufacturers build "designer" computers that come in fancy colors and command premium prices. As computer technicians, we don't usually concern ourselves with the computer case; we simply deal with whatever our customer uses. However, when it comes to recommending a computer for purchase, the size and configuration of the case should be considered. Depending on the business application, the difference between a tower and a desktop design can be important.

When considering the case, there are four general rules to keep in mind:

• The bigger the box, the more components it can hold (providing greater expansion potential) and, often, the better the air flow (essential for cooling). Large cases are also easier to work with.
• The more compact the box, the less expansion potential it has; working on it is often much more difficult, and usually air flow is more restricted.
• Smaller cases that come with a power supply usually have lower wattage, reducing the number of internal devices that can be installed.
• The more features in a case design, like the power wattage or the number of bays, the higher the cost.

IMPORTANT

It is not a good idea to run a computer for extended periods of time with the case open or removed entirely. This not only produces EMI, but also results in improper air flow and reduced cooling of the system components. If you must do so, consider placing a small fan so that it blows an air stream over the CPU and chip set

NOTE:

For more information and clarification with regard on this topics, feel free to read “A+ Certification Training Kit / Microsoft Corporation.--3rd Ed.” PUBLISHED BYMicrosoft PressA Division of Microsoft CorporationOne Microsoft WayRedmond, Washington 98052-6399 Copyright © 2001 by Microsoft Corporation