Power SupplyPower SupplyPower supply - Internet URLPower supply - Internet URL

http://www.pcguide.com/ref/power/sup/http://www.pcguide.com/ref/power/sup/index.htmindex.htm

Purpose of the Power Purpose of the Power SupplySupply

• Convert household power into a form Convert household power into a form the computer can use.the computer can use.

• Provides power to every device in the Provides power to every device in the computer.computer.

• The Power Supply converts AC The Power Supply converts AC (alternating current) which is external (alternating current) which is external power to DC (direct current) internal power to DC (direct current) internal power that the computer can use.power that the computer can use.

Roles of the Power SupplyRoles of the Power SupplyLink to the Role of the Power SupplyLink to the Role of the Power Supply

• StabilityStability – provides sufficient power to PC. – provides sufficient power to PC.• Cooling Cooling - The power supply contains the main - The power supply contains the main

fan that controls the flow of air through the PC fan that controls the flow of air through the PC case. case.

• Energy EfficiencyEnergy Efficiency - Newer PC power supplies - Newer PC power supplies work with components to reduce the amount of work with components to reduce the amount of power they consume when idle. power they consume when idle.

• Expandability Expandability -- The capacity of your power The capacity of your power supply is one factor that will determine your supply is one factor that will determine your ability to add new drives to your systemability to add new drives to your system

• A power supply is responsible for 28% of A power supply is responsible for 28% of computer problems and is 2% of the computer computer problems and is 2% of the computer cost.cost.

Household Power & Household Power & ProblemsProblems

• Household PowerHousehold Power – the external power – the external power source that comes into the wall.source that comes into the wall.

• Power ProblemsPower Problems that may lead to power that may lead to power supply problems.supply problems.– Line NoiseLine Noise– SurgesSurges– Lightening strikesLightening strikes– BrownoutsBrownouts– BlackoutsBlackouts

Line NoiseLine Noise

• Line NoiseLine Noise - Line - Line noise consists of noise consists of small variations in small variations in the voltage level the voltage level delivered to the delivered to the computer. Noise computer. Noise that the power that the power supply cannot supply cannot handle can cause it handle can cause it to malfunction and to malfunction and pass the problem on pass the problem on to your motherboard to your motherboard or other internal or other internal devicesdevices

SurgesSurges

• This is a temporary increase of This is a temporary increase of voltage that can last just a few voltage that can last just a few thousandths of a second, but in thousandths of a second, but in this time the voltage can increase this time the voltage can increase from 110 to 1,000 volts or even from 110 to 1,000 volts or even higher.higher.

• Voltage surges can disrupt or even Voltage surges can disrupt or even damage your computer equipmentdamage your computer equipment

Lightening StrikeLightening Strike

• Enormous amount of electricity involved Enormous amount of electricity involved in a storm, a strike near your PC--near in a storm, a strike near your PC--near meaning within several miles--can meaning within several miles--can induce currents in metal objects. induce currents in metal objects.

• Any wire that comes in from the outside Any wire that comes in from the outside and attaches to your PC can become a and attaches to your PC can become a conduit for a pulse of destructive energy conduit for a pulse of destructive energy such as a telephone line or power cord.such as a telephone line or power cord.

Brownout and BlackoutBrownout and Blackout

• BrownoutBrownout - when a brownout - when a brownout occurs, the voltage drops from its occurs, the voltage drops from its normal level to a lower voltage and normal level to a lower voltage and then returns; in some ways, it's then returns; in some ways, it's like the opposite of a surge. like the opposite of a surge.

• BlackoutBlackout - A blackout, of course, is - A blackout, of course, is when the power totally fails. when the power totally fails.

Parts of the Power Supply Parts of the Power Supply Internal PowerInternal Power

Parts of the Power SupplyParts of the Power Supply

• Power supplies generate high voltages internally Power supplies generate high voltages internally and can be dangerous. and can be dangerous.

• Unless you have been specifically trained to work Unless you have been specifically trained to work inside power supplies, you should not open one. inside power supplies, you should not open one.

Power Supply SpecsPower Supply SpecsInput Voltages and TolerancesInput Voltages and Tolerances

• Input Voltage RangeInput Voltage Range – acceptable – acceptable range of input – 85v-135v AC or range of input – 85v-135v AC or 170v-270v AC170v-270v AC

• Output Rating (Watts)Output Rating (Watts) – output of – output of power measured in wattspower measured in watts

Voltage Selector SwitchVoltage Selector Switch

• Normally dual Normally dual voltage selector to voltage selector to be set at either be set at either 110/220v.110/220v.

• 110 – Normal 110 – Normal voltage setting voltage setting

• 220 – For settings 220 – For settings out of the U.S.out of the U.S.

• If a 110v is set to If a 110v is set to 220v damage can 220v damage can occur.occur.

Motherboard ConnectorMotherboard Connector

• Most important Most important connection.connection.

• Supplies power Supplies power to other devices to other devices through the through the motherboard.motherboard.

• Wires are made Wires are made of copper.of copper. ATX 20

pin

Older P8 & P9

Or P1 & P2

Drive ConnectorsDrive Connectors• The power supply provides power to The power supply provides power to

internal hard disk, floppy disk, CD/DVD internal hard disk, floppy disk, CD/DVD and other drives directly, through four-and other drives directly, through four-wire connectors that are designed to wire connectors that are designed to attach to the rear of each driveattach to the rear of each drive

• The number of connectors that come with The number of connectors that come with a system may vary. a system may vary.

• There is a specific smaller floppy drive There is a specific smaller floppy drive connector.connector.

• Multiple larger four pin connectors may be Multiple larger four pin connectors may be used on hard drives, CD-ROMS, and DVD.used on hard drives, CD-ROMS, and DVD.

Drive connectorsDrive connectors

Hard drive

CD-ROM

Floppy drive

Power Supply FanPower Supply Fan

• Primary cooling source for the entire Primary cooling source for the entire PC.PC.

• Power supply fans may be made of Power supply fans may be made of different components and move different different components and move different levels of air.levels of air.

• The fan is usually the first piece of the The fan is usually the first piece of the power supply to fail because of dirt in power supply to fail because of dirt in the air.the air.

• Most computers use additional auxiliary Most computers use additional auxiliary fans to help cool the entire PC.fans to help cool the entire PC.