CPT03

• Power Supply


  Converts the alternating current (AC) from mains to the direct current (DC) needed by the computer
• Power Supply


  • Typical voltages produced: 3.3 volts, 5 volts, 12 volts
  • 3.3-volts and 5-volts used by digital circuits, 12-volt used to power fans and motors in disk drives
• Power Supply Wattage


  A watt is the product of the voltage in volts and the current in amperes or amps
• A 400-watt switching power supply will not necessarily use more power than a 250-watt supply
• It is not a good idea to have a 250-watt supply if you have 250 watts total in devices, since the supply should not be loaded to 100 percent of its capacity
• Power consumption values (in watts) for common items in a personal computer

  • AGP Video Card: 30W - 50W
  • PCI Express Video: 100W - 250W
  • Average PCI Card: 5W - 10W
  • DVD/CD: 20W - 30W
  • Hard Drive: 15W - 30W
  • Case/CPU Fans: 3W (ea.)
  • Motherboard (w/o CPU or RAM): 50W - 150W
  • RAM: 15W per 1GB
  • Processor: 80W - 140W
• For overall power supply wattage, add the requirement for each device in your system, then multiply by 1.5
• Heat Sinks


  A heat exchanger component attached to a device used for passive cooling, designed to increase the surface area in contact with the cooling fluid surrounding it, such as the air thus allowing it to remove more heat per unit time
• Fans


  Any fan inside, or attached to, a computer case used for active cooling, and may refer to fans that draw cooler air into the case from the outside, expel warm air from inside, or move air across a heat sink to cool a particular component
• Computer Case


  The enclosure that contains most of the components of a computer (usually excluding the display, keyboard and mouse)
• Computer Case


  • The size and shape of a computer case is usually determined by the form factor of the motherboard
  • Personal computer form factors typically specify only the internal dimensions and layout of the case
  • Full-size tower cases are typically larger in volume than desktop cases, with more room for drive bays and expansion slots
  • Desktop cases—and mini-tower cases designed for the reduced microATX form factor—are popular in business environments where space is at a premium
• Major Component Locations in a Computer Case

  • Motherboard
  • I/O ports and expansion slots
  • Power supply unit
  • Drive bays
  • Buttons and LEDs
  • Vents

  
• Manufacturers: Asus, Foxconn
• Motherboard


  The key circuit board holding the essential processing parts of a computer, allowing all the parts to receive power and communicate with one another

  
• Motherboard


  • Usually screwed to the case along its largest face, which could be the bottom or the side of the case depending on the form factor and orientation
  • The form factor describes the shape and layout of the motherboard, affecting where individual components go and the shape of the computer's case
  • Attached directly to the motherboard are the CPU, RAM, expansion cards, networking, video, and other components

  
• Motherboard is the key circuit board holding the essential processing parts of a computer

  
• Motherboard


  Allows all the parts of your computer to receive power and communicate with one another

  
• Motherboard


  • Usually screwed to the case along its largest face, which could be the bottom or the side of the case depending on the form factor and orientation
  • The form factor describes the shape and layout of the motherboard and affects where individual components go and the shape of the computer's case

  
• Components attached directly to the motherboard


  • CPU
  • RAM
  • Expansion cards
  • Networking
  • Video
  • Audio

  
• ATX (Advanced Technology eXtended)


  A motherboard form factor specification developed by Intel in 1995

  
• ATX motherboard


  • Full-size ATX board is 12 × 9.6 in (305 × 244 mm)
  • The specification defines the key mechanical dimensions, mounting point, I/O panel, power and connector interfaces between a computer case, a motherboard, and a power supply
  • The specification has been revised numerous times since 1995, the most recent being version 2.3, released in 2007

  
• Standards for smaller boards

  • microATX
  • FlexATX
  • mini-ITX
• Expansion cards are one way to add new types of ports to an older computer or to expand the number of ports on your computer
• Expansion card


  • 3 USB ports and 2 Firewire ports
• Video (Graphics) Card


  An expansion card installed inside your system unit to translate binary data received from the CPU or GPU into the images you view on your monitor

  
• Video Card


  • Contains its own RAM, called video memory
  • Includes its own processors or GPUs, so calls to the CPU for graphics processing are redirected to the processor on the video card, significantly speeding up graphics processing
  • Controls the number of colors your monitor can display based on the bit depth used to represent each pixel

  
• Video Card Manufacturers


  • Nvidia (GeForce 4)
  • AMD (Radeon)

  
• Sound Card


  Enabled your computer to record and reproduce sounds
• Sound Card


  • Most computers ship with a basic 3D sound card, which is better than stereo sound at convincing the human ear that sound is omnidirectional
  • To set up surround sound, you need a sound card that is Dolby Digital compatible and a set of surround-sound speakers
  • The ports on the sound card allow you to connect additional audio devices such as amplified speakers, headphones, microphones etc.
• Network Card


  An Ethernet network adapter that allows a computer to be connected to a network
• RAM (Random Access Memory)


  A series of small cards or modules plugged into slots on the motherboard that provide temporary or volatile storage for the computer

  
• How DRAM works


  1. Memory cells are etched onto a silicon wafer in an array of columns (bitlines) and rows (wordlines)

  2. DRAM sends a charge (electrical signal called a strobe) through the appropriate column (CAS) to activate the transistor at each bit in the column

  3. When writing, the row lines contain the state the capacitor should take on. When reading, the sense-amplifier determines the level of charge in the capacitor

  4. The counter tracks the refresh sequence based on which rows have been accessed in what order

  5. The memory controller performs functions like identifying the type, speed and amount of memory and checking for errors

  
• Physical Memory


  The amount of RAM actually sitting on memory modules in your computer

  
• Kernel Memory


  The memory that your operating system uses
• To determine how much RAM your computer needs, look at the memory requirements for each program and add them up

  
• Sample RAM requirements


  • Windows 7: 1000 MB
  • Microsoft Office Professional 2007: 256 MB
  • Internet Explorer 8: 128 MB
  • iTunes: 256 MB
  • Adobe Photoshop Elements: 512 MB
• To save data more permanently, you need to save it to the hard drive or to another permanent storage device such as a CD or flash drive
• Read-only memory (ROM)


  Holds all the instructions the computer needs when it is powered on, and the data does not get erased when the power is turned off

  
• Bus width


  The number of bits that can be sent to the CPU simultaneously
• Bus speed


  The number of times a group of bits can be sent each second