The Computer Case
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. It often represents the identity of a specific brand of computer, and, sometimes, it is even part of the reason we purchase a particular computer. We do, after all, want something that looks good, especially if we are spending a lot of money on it.
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.
The real value of a case does not lie in the label, color, or how pretty it looks. The case houses all the internal components, offers access to the outside world (ports and connectors), and protects the PC's delicate circuits from damage and electromagnetic interference. And it 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 into the surrounding area. Running a computer without its cover is a sure way to generate EMI.
As computer technicians, we don't usually concern ourselves with the computer case; we simply deal with whatever our customer already has. 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 could be important.
When considering the case, there are three general rules to follow:
- The bigger the box, the more components it can hold (the greater the expansion potential) and, often, the better the airflow (essential for cooling). Large cases are 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 airflow is reduced.
- Smaller cases that come with a power supply usually have lower wattage, once again reducing the number of internal devices that can be installed.
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 airflow and reduced cooling of the system components.