Chapter 4
multimeter
A more general-purpose tool that can measure several characteristics of electricity in a variety of devices.
voltage selector switch
A power supply might have a voltage selector switch on the back. Often, the voltage selector switch on the power supply can be set to 230 V or 115 V. When in the United States, set the switch to 115 V. Be sure to never change the switch setting until you first turn off and unplug the power supply.
ATX12V power supply
A power supply that provides a 12 V power cord with a 4-pin connector to be used by the auxiliary 4-pin power connector on motherboards used to provide extra power for processors.
POST (power-on self test)
A series of tests performed by the startup BIOS when you first turn on a computer.
form factor
A set of specifications on the size, shape, and configuration of a computer hardware component such as a case, power supply, or motherboard.
ground bracelet
A strap you wear around your wrist. The strap has a cord attached with an alligator clip on the end. Attach the clip to the computer case you are working on to prevent static electricity. It is also called an antistatic wrist strap or ESD bracelet.
daughter card
A subordinate extension of a motherboard.
data line protector
A surge protector designed to work with the telephone line to a modem.
notebook case
A type of case used for portable notebook computers.
spikes
Temporary surges in voltage, which can damage electrical components. Also called swells.
intelligent UPS
A UPS connected to a computer by way of a USB or serial cable so that software on the computer can monitor and control the UPS. Also called smart UPS.
diagnostic card
A card that is useful when troubleshooting errors with hardware.
riser card
A card that plugs into a motherboard and allows for expansion cards to be mounted parallel to the motherboard. Expansion cards are plugged into slots on the riser card.
field replaceable unit (FRU)
A component in a computer or device that can be replaced with a new component without sending the computer or device back to the manufacturer. Examples: power supply, DIMM, motherboard, floppy disk drive.
uninterruptible power supply (UPS)
A device designed to provide a backup power supply during a power failure. Basically, a UPS is a battery backup system with an ultra-fast sensing device.
surge protector or surge suppressor
A device or power strip designed to protect electronic equipment from power surges and spikes.
transformer
A device that changes the ratio of current to voltage. A computer power supply is basically a transformer and a rectifier. A+ Guide to Managing and Maintaining your PC, 7e 4-19 À transistor: An electronic device that can regulate electricity and act as a logical gate or switch for an electrical signal.
inverter
A device that converts DC to AC.
line conditioner
A device that regulates, or conditions, power, providing continuous voltage during brownouts and spikes.
soft switch
A feature on an ATX or BTX system that allows an OS to power down the system and allows for activity such as a keystroke or network activity to power up the system. Also called soft power.
power conditioner
A line conditioner that regulates, or conditions, power, providing continuous voltage during brownouts.
NLX
A low-end form factor that is similar to LPX but provides greater support for current and emerging processor technologies. NLX was designed for flexibility and efficiency of space.
electromagnetic interference (EMI)
A magnetic field produced as a side effect from the flow of electricity. EMI can cause corrupted data in data lines that are not properly shielded.
volt (V)
A measure of potential difference in an electrical circuit. A computer ATX power supply usually provides five separate voltages: +12 V, -12 V, +5 V, -5 V, and +3.3 V.
joule
A measure of work or energy. One joule of energy produces one watt of power for one second.
compact case
A type of case used in low-end desktop systems. Compact cases, also called low-profile or slim-line cases, follow either the NLX, LPX, or Mini LPX form factor. They are likely to have fewer drive bays, but they generally still provide for some expansion.
ampere or amp (A)
A unit of measurement for electrical current. One volt across a resistance of one ohm will produce a flow of one amp.
line-interactive UPS
A variation of a standby UPS that shortens switching time by always keeping the inverter that converts AC to DC working, so that there is no charge-up time for the inverter.
FlexATX
A version of the ATX form factor that allows for maximum flexibility in the size and shape of cases and motherboards. FlexATX is ideal for custom systems.
MicroATX
A version of the ATX form factor. MicroATX addresses some new technologies that were developed after the original introduction of ATX.
bus riser
Also called a riser card.
Midsize towers
Also called midi-towers or mid-towers, are the most versatile and most popular tower case.
power supply
Also known as a power supply unit (PSU). A box inside a computer case that supplies power to the motherboard and other installed devices.
static electricity
An electrical charge at rest. Also known as electrostatic discharge (ESD).
electrostatic discharge (ESD)
An electrical charge at rest. Also known as static electricity.
rectifier
An electrical device that converts AC to DC. A PC power supply contains a rectifier.
diode
An electronic device that allows electricity to flow in only one direction. Used in a rectifier circuit.
capacitor
An electronic device that can maintain an electrical charge for a period of time and is used to smooth out the flow of electrical current. Capacitors are often found in computer power supplies.
resistor
An electronic device that resists or opposes the flow of electricity. A resistor can be used to reduce the amount of electricity being supplied to an electronic component.
sag
Another term for a brownout.
low-profile case
Another term for a compact case.
soft power
Another term for a soft switch.
smart UPS
Another term for intelligent UPS.
alternating current (AC)
Current that cycles back and forth rather than traveling in only one direction. In the United States, the AC voltage from a standard wall outlet is normally between 110 and 115 V. In Europe, the standard AC voltage from a wall outlet is 220 V.
direct current (DC)
Current that travels in only one direction (the type of electricity provided by batteries). Computer power supplies transform AC to low DC.
radio frequency interference (RFI)
EMI in the radio frequency range.
DIP (dual inline package) switch
On/off switches used on older motherboards to configure the board.
P1 connector
Power connection on an ATX or BTX motherboard.
overclocking
Running a processor, motherboard, or video card at a higher frequency than the manufacturer recommends and is not considered a best practice. It might also void the warranty of a component.
antistatic wrist strap
See ground bracelet.
brownouts
Temporary reductions in voltage, which can sometimes cause data loss. Also called sags.
desktop case
The initial screen that is displayed when an OS has a GUI interface loaded.
tower case
The largest type of personal computer case. Tower cases stand vertically and can be as high as two feet tall. They have more drive bays and are a good choice for computer users who anticipate making significant upgrades.
BTX (Balanced Technology Extended)
The latest form factor expected to replace ATX. It has higher quality fans, is designed for better air flow, and has improved structural support for the motherboard.
clamping voltage
The maximum voltage allowed through a surge suppressor, such as 175 or 330 volts.
ATX
The most common form factor for PC systems presently in use, originally introduced by Intel in 1995. ATX motherboards and cases make better use of space and resources than did the AT form factor.
ohm (Ω)
The standard unit of measurement for electrical resistance. Resistors are rated in ohms.
watt (W)
The unit used to measure power. A typical computer may use a power supply that provides 200 W
power supply tester
Used to measure the output of each connector coming from the power supply.
slimline case
another term for compact case.
swell
another term for spike.