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PC Upgrade & Repair Simplified
By Paul Whitehead
John Wiley & SonsISBN: 0-7645-3560-9
Chapter OneCOMPUTER ESSENTIALS
Do you want to familiarize yourself with the components a computer requires to operate before you begin an upgrade or repair? This chapter explains the system board, central processing unit and much more.
Computer Case 30 System Board 32 Power Supply 38 CPU 42 Memory 46 Expansion Card 54
A computer case is a box that contains most of the major components of a computer system. A computer case provides a solid structure that protects components from dirt and damage.
When upgrading or repairing a computer, you will often need to remove the computer case cover.
REMOVE A COMPUTER CASE COVER
Before removing the computer case cover, turn off the computer and unplug the power cable.
1 Remove the screws that hold the computer case cover in place. Most covers are held in place by four screws at the back of the computer.
You can check your computer's documentation to determine which screws to remove. Some of the screws at the back of the computer secure internal devices, such as the power supply, to the computer.
2 Slide the cover backward or forward a short distance. Then lift the cover straight up.
SET UP A COMPUTER CASE
Most computer cases have items, such as the power button and indicator lights, which attach to pin connectors on the system board. To avoid problems, make sure you connect all the items properly.
CHOOSE A COMPUTER CASE
Computer Case Style
There are two main styles of computer cases-desktop and tower. A desktop case is wider than it is tall and usually sits on a desk, under a monitor.
A tower case often sits on the floor. This provides more desk space, but can be less convenient for inserting and removing floppy disks and CD-ROM discs.
A form factor is a set of specifications that determines the internal size and shape of a computer case. The two most popular computer case form factors are ATX and Baby AT. The computer case must use the same form factor as the power supply and system board.
Computer cases are often sold with a power supply already installed. When purchasing a new computer case, you should ensure that the power supply meets your power requirements. For more information about power supplies, see page 38.
A system board is the largest and most complex component in a computer.
REPLACE A SYSTEM BOARD
Before replacing a system board, turn off the computer, unplug the power cable and remove the cover from the computer case. Then ground yourself and the computer case. For information about grounding, see page 6.
1 Disconnect the cables from the back of the computer. Then remove the expansion cards from the system board.
2 Disconnect all the cables from the system board.
3 Remove all the screws that secure the system board in the computer case.
4 Slide the system board slightly sideways to release the small plastic spacers, called standoffs, that prevent the system board from touching the computer case. Then lift the system board out of the computer case.
5 If necessary, add the standoffs from the old system board to the new system board.
6 Place the new system board in the computer case, slide the system board into position and secure it with screws. Then reconnect all the cables, re-install the expansion cards and replace the cover on the computer case.
MAIN SYSTEM BOARD COMPONENTS
A port allows the system board to communicate with an external device, such as a printer.
The power connector is a socket on the system board. The system board power cable attaches to the power connector.
An expansion slot is a socket on the system board. An expansion card, which lets you add features to a computer, plugs into anexpansion slot.
The Basic Input/Output System (BIOS) chip controls the transfer of data between devices attached to the system board.
A memory slot is a socket on the system board. A memory module, which holds memory chips for storing data, sits in a memory slot.
The Complementary Metal Oxide Semiconductor (CMOS) chip saves the time and the computer's BIOS settings. A battery provides power to the CMOS chip when the computer is turned off.
A chipset is a series of chips that contains instructions for controlling the movement of data through the system board.
Cache memory stores recently used data.
Jumpers allow you to adjust the settings for the system board.
The processor socket holds the CPU, which is the main chip in a computer.
A form factor is a set of specifications that determines the general size and shape of a system board. The Baby AT form factor is found in many older computers, but most newer computers use the ATX form factor. The system board you choose must use the same form factor as the computer case and power supply.
The type of processor socket determines the type of CPU you can use in the computer. A square, two-inch socket, called Socket 7, holds a Pentium CPU. Pentium II, Celeron and Pentium III CPUs fit into a socket similar to an expansion slot, called Slot 1.
Most system boards offer Advanced Power Management (APM) features, which allow you to conserve energy by controlling how a computer uses power after a period of inactivity. For example, you can have your hard drive, monitor and other devices shut down when they are not in use.
Each system board has a series of chips that contains instructions to control the movement of data through the system board. When you purchase a system board, make sure the chipset is compatible with your CPU.
Cache memory is used to speed up the transfer of data by storing data the computer has recently used. Cache memory is faster and more expensive than main memory. Many new system boards come with 512 K of cache memory.
The system bus carries data between components on the system board. Most new system boards support bus speeds of 100 and 133 megahertz (MHz). System boards that use Pentium 4 CPU chips can support bus speeds starting at 400 MHz.
Expansion buses carry data between devices in a computer. There are three common types of expansion bus-Industry Standard Architecture (ISA), Peripheral Component Interconnect (PCI) and Accelerated Graphics Port (AGP).
Depending on the type of memory in the computer, memory speed may be measured in nanoseconds (ns) or megahertz (MHz). When upgrading your system board, make sure the system board supports the speed of your existing memory. For information about memory, see page 46.
The Basic Input/Output System (BIOS) chip controls the transfer of data between devices. When you turn on the computer, the BIOS chip automatically examines each device and adjusts the system board settings to ensure the devices work properly. For information about BIOS settings, see page 146.
My system board is not working properly. What should I do?
A problem with a system board is often caused by a malfunctioning component, such as a faulty memory module. To find the component causing the problem, remove a component not required for basic operation and then start the computer to determine if the problem still exists. Repeat this procedure with different components until you discover which component is causing the problem.
My system board and components are not faulty. Why am I experiencing problems?
Problems such as computer lockups may actually be caused by a loss of power or a computer virus. See page 38 for information about protecting your computer from a loss of power. See page 22 for information about computer virus protection.
Is there software I can use to test my system board?
Diagnostic software allows you to test your system board. For example, diagnostic software can help you determine if all the ports on the computer are working properly. You can purchase diagnostic software at most computer stores.
How can I determine if my system board's settings are correct?
Check the documentation included with your system board or computer to determine if the system board settings are correct. Incorrect system board settings, such as an incorrect bus speed, can cause problems with the computer such as a lockup or failure to start.
How do I prevent my computer from overheating?
The CPU and other components inside the computer case generate heat. Overheating may cause the computer to malfunction. To prevent overheating, make sure the fan inside the computer is working properly. Many system boards have a built-in thermometer that will shut down the computer before it overheats.
How do I clean my system board?
You can use a can of compressed air to blow away the dust and dirt on your system board. If the system board is extremely dusty, you may need to remove the cables and components from the system board before cleaning.
A power supply changes the alternating current (AC) that comes from an electrical outlet to the direct current (DC) that a computer can use.
REPLACE A POWER SUPPLY
Before replacing a power supply, turn off the computer, unplug the power cable and remove the cover from the computer case. Then ground yourself and the computer case. For information about grounding, see page 6.
Disconnect the power supply cables from the system board and other devices inside the computer.
If necessary, remove the front of the computer case and unfasten the power switch from the front of the computer.
Remove the screws that secure the power supply in the computer case. Then slide the power supply out of the computer case.
Slide the new power supply into the computer case and use screws to secure it.
Reconnect all the cables. If necessary, reconnect the power switch and replace the front of the computer case. Then replace the cover on the computer case.
Verify the Problem
Power supplies tend to be very reliable and usually work for many years without any problems. Symptoms of a faulty power supply can include the computer locking up repeatedly or other components failing to work consistently.
Before replacing a power supply, make sure the problems you are experiencing are not caused by another component, such as a malfunctioning hard drive.
Excerpted from PC Upgrade & Repair Simplified by Paul Whitehead Excerpted by permission.
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