A+ Core 1 (220-1101) Cram Notes

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1. PC Hardware

1.7 Compare and contrast various connection interfaces and explain their purpose.

  • Bluetooth is widely used for communication between smart phones and other accessories or between PDAs and information kiosks. The typical coverage for Bluetooth devices is up to 30 feet. It can be used for personal area networking devices like keyboards and headphones

  • High-Definition Multimedia Interface (HDMI) connectors are used to connect compatible digital items (DVD players and conference room projectors, for example).

  • DVI differs from everything else in that it includes both digital and analog signals at the same time, which makes it popular for LCD and plasma TVs. Any TV that has DVI D/I input should also have a seperate audio jack next to the DVI socket, probably a mini-jack

  • VGA connections and cables are analog in nature

  • DisplayPort is a digital interface standard produced by the Video Electronics Standards Association (VESA), used for audio and video.

1.8 Install an appropriate power supply based on a given scenario.

DC voltages commonly found in a PC:

a. +5, and +12 volts are the DC voltages commonly found on PCs.80386 / 486 operate at +5v
b. Pentium and above operate at +3.3v
c. Power supply wires - yellow=+12v, blue=-12v, red=+5v, & white=-5v

  • One good way of determining a bad power supply is that the fan will not rotate. Also, the computer will not boot and the LED s indicating the power and disk activity will be OFF.

  • ATX12V 2.0 power supply provides four different voltages. 3.3Volts, 5Volts, 12Volts and -12Volts. Previous versions of ATX12V used to provide -5V, and it has been discontinued in version 2.x.

  • ATX style systems use two power connectors, P8 and P9 to connect to the motherboard. ATX systems use only one P1 connector to connect to the motherboard.

  • Uninterrupted Power Supply (UPS):An UPS is required for any critical and un-interrupted use of computers. It has the following benefits:

a. Provide protection against small surges
b. Filters noise from entering the computer
c. Provide power to the computer during line power failure
d. Give stable power to computer, even when the line power is unstable.

  • Note that the UPS can give un-interrupted power only for a fixed amount of time under a given load, in the absence of line voltage

  • Some PCI Express Graphics cards require extra power.High-end graphics cards will consume from 75 watts up to 150 watts of power. The PCI Express x16 connector can deliver up to 75 watts. In order to achieve 75W, an ATX12V power supply with a 2x12 main power connector is recommended. 25W-75W graphics cards are powered through the desktop board's PCI Express x16 connector. For additional power requirement, a new connector on the graphics card has been designed to supply up to 150 watts. This means an entirely new power supply will be required for some new graphics cards.

  • When selecting a power supply, two issues become important. You need to supply the total wattage required by all the devices and the motherboard of the PC, and you must ensure that it has the connector types required by your devices.

  • SATA: The SATA power connector is 15 pins, with 3 pins designated for 3.3 V, 5 V, and 12 V, with each pin carrying 1.5 amps. This results in a total draw of 4.95 watts + 7.5 watts + 18 watts, or about 30 watts.

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