A_2006_In_Depth_Chapter04

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Chapter 04Form Factors and Power Supplies


Form Factors and Power Supplies  In this chapter you will learn:  About different form factors and computer

cases  How electricity is measured  How to protect your computer system against damaging changes in electrical power  How to troubleshoot electrical problems


Computer Case, Motherboard and Power Supply Form Factors-pg.132 ď Ž Form Factor: describes the size, shape

and major features of a hardware component ď Ž Chassis: another word for computer case


Types of Form Factors-pg.133  BTX, ATX, LPX, NLX, Backplane Systems

and the outdated ATX Most Common:  ATX, MicroATX, BTX and NLX


AT Form Factor  Sometimes called “Full AT”  Measures at 12” x 13.8”  Supplies the system with +5, -5, +12, -12

Volts DC  P8 and P9 Power Connector


Baby AT Form Factor pg.134  Smaller version of the AT form

factor  Backwards compatible with the AT form factor  Used from 1993 to 1997


ATX Form Factor  Most commonly used today  Developed in 1995 by Intel  Better position of components  Reduced potential of EMI (Electro

magnetic interference)  Measures 12” x 9.6” so its smaller that an AT motherboard


ATX Form Factor  The first ATX power supplies and

motherboards used a P1 power connector  Provide the computer with: -3, +3, -5, +5, -12, +12 volts of DC current  P1 connector uses 20 pins and ATX ver.2.2 uses 24 pins  Power supplies with the extra 4 pins are also called ATX12V


MicroATX Form Factor pg.137  Variation of the ATX  Reduces cost by reducing I/O ports  Smaller power supply  Smaller case


BTX Form Factor  BTX (Balanced Technology Extended)  Designed by Intel to be used by everything

big and small  Takes full advantage of SATA, USB 2.0 and PCI Express  Use a 24 pin power connector  Improved wind tunnel effect pg.138


LXP and Mini-LPX Form Factors  Developed by Western Digital  One expansion slot with a riser card or

bus riser or daughter card  Uses low profile cases and slim line cases  Can only use the manufacturers power supplies


NLX Form Factor ď Ž Low end personal computer motherboard

developed by Intel in 1998 ď Ž Improvement over LPX


Backplane Systems  Do not use a true motherboard  Active backplanes contain bus connectors,

buffer and driver circuits  Passive backplanes contain not circuitry at all  Used for rack mounted systems  Built for easy access


Types of cases pg.140  Desktop cases  Tower cases


Desktop Cases  Desktop case doubles as a monitor stand  Low end desktops: compact cases, low-

profile cases or slim line cases  Use the NLX, LPX and Mini-LPX form factor


Tower Cases  Tower cases can be as high as two feet  Often used for servers  Good for upgrading  Use the ATX, Mini-ATX and BTX form

factors


Notebook Cases ď Ž Proprietary- Can only be purchased from

the vendor. Example: Dell, Toshiba, Sony etc. ď Ž All are different in size and power supply, no set standards.


Measures and Properties of Electricity pg.143


AC and DC  AC-Alternating Current  AC goes back and forth (oscillates) at

60Hz or 60 times in one second  Alternates from -110v to +110v


AC and DC      

DC-Direct Current Travels in only one direction Most electronics use DC A rectifier converts AC to DC like in a power supply A transformer changes the amount of current A power supply uses a rectifier and a transformer


Hot, Neutral and Ground pg.144  Hot-the hot connector is the source of the

electricity  Neutral-the neutral connectors is the path back to the power station for the electricity  Electricity flows from Hot to Neutral  Ground is an escape route for out of control electricity like in a short


Hot, Neutral and Ground Fuses ď Ž Fuses are rated in AMPS ď Ž They are made to prevent too much current from flowing through a circuit


Receptacle Tester ď Ž A receptacle tester is used to verify that

hot, neutral and ground are wired correctly


Some Common Electrical Components pg.146 ď Ž Transistor- serves as a gate or a switch for

an electrical signal and can amplify the flow of electricity.


Some Common Electrical Components  Capacitor- an electronic device that can

hold an electrical charge for a period of time and can smooth the uneven flow of electricity through a circuit.  Used in power supplies  Can be dangerous even when unplugged


Some Common Electrical Components ď Ž Diode-allows electricity to flow in only one

direction. ď Ž One to four diodes in various configurations is called a rectifier and is used to convert AC to DC


Some Common Electrical Components  Resistor- a resistor limits the amount of

current that can flow through it.  Used to protect a circuit from over load  Resistors are color coded to indicate the level of resistance measured in Ohms


DC


Fuse


Capacitor


Wall Outlet


Diode


Resistor


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