Inside the Computer
Opening the case
Warning! Before deciding to open your computer case and touch or remove any parts inside, you should be aware that your body can contain static electricity that may be discharged to the circuits inside your computer. A static discharge can damage or ruin your computer. Therefore prior to doing any work inside your computer, you should get a grounding strap. A grounding strap can be attached to one of your wrists and be plugged into the wall (if it is the type made for a wall outlet). If you don't have the ground strap made for the wall outlet, you may need to attach your ground strap to a cold water pipe. A ground strap grounds your body using the earth ground in the wall outlet or from a cold water pipe. A grounding strap should cost less than twenty dollars and should be available at an electrical equipment store. You should always wear a ground strap when working inside your computer case. Especially when working with the microprocessor, memory, motherboard, or other plug in boards.
Warning! Hazard! Prior to opening your computer case, be sure it is turned off and unplugged. 110 volts can cause injury or death! Also working on your computer while it is plugged in can damage or destroy it.
To open the computer case, depending on the type of case you may need to follow one of the following sets of instructions.
- For the less expensive cases normally you need to:
- Remove 4 or 5 screws in the back of the case. Be sure these screws hold the case and not some other component like the power supply.
- Slide the case foreword on its slots and remove it.
- For higher quality cases
- Remove one thumbscrew or one or two phillips head screws from the back of your case that may hold one or more panels.
- Remove the top panel and/or one or more necessary side panels.
Once you have opened the case, lay it on its side so you can look at the inside components. You should see some variation of the following picture.
In the picture, the front of the computer is at the bottom and the rear is at the top. At the front (bottom of the picture) are normally two metal bays made to enclose hard drives, floppy drives, and CD-ROM drives. There is a 5.25 inch and a 3.5 inch set of bays. Most hard drives will mount into the smaller 3.5 inch bays with the CD-ROMS mounting in the 5.25 inch bays. The hard floppy, and CD-ROM drives are mounted to their enclosures with screws on their left and right sides. The power supply is on the top right side of the picture which when the computer is in its normal standing position is the top rear. At this location it will draw the warm air that naturally rises to the top of the case to the outside.
Between the hard, floppy, and CD-ROM drive bays you will see some thin flat grey cables going to the floppy and hard drive connectors on the motherboard. These are data/control cables used by the system to control the drives and get and send data from and to them. On one side of the grey cable should be a red stripe going along the cable. This red stripe should always be placed on the pin 1 side of the connector. You will need to look closely at the connectors on your hard and floppy drives to determine which is the pin 1 side or read your manual. On hard drives and most CD-ROMs pin 1 is on the side closest to the power supply connector.
Cables running between the power supply are colored black, red, and yellow. There is one going to each hard drive, floppy drive, CD-ROM drive and any other drive the system is using such as a mass storage device. There is also a multicolored power supply cable with about 12 wires going between the power supply and the motherboard. The wires are colored black, red, yellow, orange, and there is one that is blue. The connector on this cable should be keyed so it cannot be inserted the wrong way. Also some of the data cables are keyed, but others are not. It varies a little from system to system.
The power supply
The primary rating on the power supply that you should be concerned about is wattage. Most are standard in the range from 230 through 300 watts. I recommend 250 watts for most standard systems today. If you are buying a high powered system with a microprocessor that uses a lot of power such as an AMD Athlon, you will need to buy a case that has a power supply capable of providing 300 watts.
The following sections talk about the motherboard and associated components such as memory, the microprocessor, and the expansion cards.