II. Parts: Motherboard (system board, logic boards)

  1. Background
    1. Printed circuit board (PCB) typically made of fiberglass
    2. Embedded copper to transmit signals (via bus) between components
      1. To/From CPU, memory and I/O via control bus, address bus and data bus
    3. Slots for CPUs, Chipsets (north and south), CMOS/battery, power, memory, PCI expansion, output
    4. Often sold without processor, case or power supply
      1. Described form factor (e.g. ATX)
      2. Described with CPU slot (e.g. LGA 1150) and chipset (Intel Z97) to match CPU compatibility
      3. Described ports (e.g. USB 3), drive interface (e.g. SATA)
      4. Memory types (e.g. DDR3 and speeds)
  2. Motherboard form-factors
    1. Advanced Technology Extended (ATX) - Intel, standard, full-sized case motherboard since 1995
    2. Micro-ATX (small form factor, 6.75" square or 9.6" square) - same components/slots as ATX, in a smaller space
    3. Mini-ATX (very small form factor)
  3. Miscellaneous parts
    1. System clock
      1. Quartz crystal oscillator sets clock cycles per second (typically 3-4 GHz or 3-4 Billion cycles/second)
      2. Sets the timing of CPU, devices and memory instruction processing
      3. https://en.wikipedia.org/wiki/Clock_rate
  4. Utilities: Windows (show BIOS and UEFI settings, as well as CPU)
    1. CPU-Z
    2. Piriform Speccy

III. Parts: Chipsets

  1. North Bridge (or Memory Controller Hub, MCH)
    1. High speed bus between processor, memory and PCI-Express graphics card
    2. Processor connects to north bridge chipset via the front-side bus
    3. Modern processors (e.g. Intel i7) include much of the north bridge functionality
      1. Intel i7 includes memory controller and PCIe connector
    4. https://en.wikipedia.org/wiki/Northbridge_(computing)
  2. South Bridge (or IO Controller Hub, ICH)
    1. Lower priority devices (e.g. input-output devices)
    2. Integrated graphics is typically connected to processor via south bridge
    3. https://en.wikipedia.org/wiki/Southbridge_(computing)

IV. Parts: Central Processing Unit (CPU)

  1. See Motherboard (above) for CPU-Z and other utilities to examine CPU
  2. Processor Slot
    1. Zero Insertion Force (ZIF)
      1. Old, fragile form where numerous tiny pins projected from underside of chip (Nightmare insertion)
      2. Used by AMD
        1. AMD sockets (e.g. AM3, AM3+, FM1, FM2) all have 900-950 contacts
      3. https://en.wikipedia.org/wiki/Zero_insertion_force
    2. Land Grid Array (LGA)
      1. Newer form where numerous flat contacts (gold-plated copper) on the chip underside, contact the socket's pins
      2. CPU enclosure pushes the chip against the socket to ensure adquate contact
      3. Used by Intel
        1. Intel socket types are named for number of individual contacts (e.g. LGA 1150 has 1150 contacts)
        2. Intel Chips with >1150 contacts incorporated integrated Northbridge (e.g. LGA 1366)
        3. Some high end chips have over 2000 contacts (e.g. LGA 2011 which allows for 6 core chips)
      4. https://en.wikipedia.org/wiki/Land_grid_array
  3. Bus
    1. Internal Registers of CPU connect to memory via Bus
    2. Data is passed via a data bus and memory locations (reference for data location) are passed via address bus
    3. https://en.wikipedia.org/wiki/Bus_(computing)
  4. Cores
    1. Each processor core operates independently from other processors (twice as much work is done by 2 processors than 1)
    2. Hyperthreading can simulate additional cores (e.g. 2 per physical core)
      1. Each hyperthreaded core still runs serially through the physical core, so not as fast as an extra real physical core
    3. https://en.wikipedia.org/wiki/Multi-core_processor
  5. Cache
    1. Processor cores have shared cache (e.g. Intel L3 cache might be 2 MB)
    2. Each processor core typically has its own dedicated on-chip memory cache (e.g. Intel L1 and L2 cache)
      1. Intel L1 cache is fastest, low latency Static RAM, but only, e.g. 64 kb
      2. Intel L2 cache is not as fast as L1, but larger, e.g. 512 kb
  6. Clock Speed
    1. Number of instructions performed by CPU per second (typically 3-4 GHz or 3-4 Billion cycles/second)
    2. https://en.wikipedia.org/wiki/Clock_rate
  7. Virtualization (Intel VT-X, AMD-V)
    1. Processor instructions allow system to create a virtual machine (e.g. VMware) in software as if it existed in hardware
    2. Must be enabled via UEFI
    3. https://en.wikipedia.org/wiki/Virtualization
  8. Architecture
    1. CPU 32 bit
      1. Addresses up to 4 Billion RAM addresses (4 GB = 2^32 bits)
      2. https://en.wikipedia.org/wiki/32-bit
    2. CPU 64 bit
      1. Addresses up to 18 Quintillion RAM addresses (16 Exbibytes = 2^64 bits)
      2. https://en.wikipedia.org/wiki/64-bit_computing
  9. Chip functionality
    1. High end chips incorporate more functionality (e.g. Intel Haswell includes 4 cores and graphics processor on the CPU)
  10. NX Bit (No Execute bit) or XD Bit (Intel's Execute Disable) or XN Bit (Arm's Execute Never)
    1. Security feature on come modern CPUs that mark certain memory areas for non-executables (e.g. storage)
    2. https://en.wikipedia.org/wiki/NX_bit
  11. Cooling
    1. Heat Sink and often a fan sit atop processor for cooling (may sit under a plastic shroud)
    2. Thermal paste applied top of CPU to allow for heat dissipation to heat sink and then fan
    3. Liquid-based cooling (often noisy) and controversial regarding benefit over standard sink and fan
      1. Should cool CPU, GPU and chipset
    4. CPU expose their Temperature data and can be visualized in UEFI, CPU-Z or dedicated utilities (e.g. Core Temp, SpeedFan)
    5. https://en.wikipedia.org/wiki/Computer_cooling#Spot_cooling

V. Parts: BIOS

  1. See Motherboard (above) for CPU-Z and other utilities to examine BIOS and UEFI
  2. Complimentary-Metal Oxide Semiconductor (CMOS)
    1. Electronically Erasable Programmable Read-Only Memory (EPROM) Chip
    2. Holds hardware settings and BIOS, and BIOS updates are flashed to this chip
    3. CMOS maintains a constant low power (even with system unplugged) via 2 button batteries (2032)
      1. When these batteries start to fail, system clock will lose time, and ultimately system settings are lost
  3. Basic Input/Output System (BIOS)
    1. Firmware installed on CMOS chip, with instructions for hardware initialization on system boot
    2. Includes, for example, disk boot priority and other I/O, over-clocking and virtualization
  4. Unified Extensible Firmware Interface (UEFI)
    1. Extends BIOS firmware on modern systems
    2. Overcomes BIOS limitations (64 bit processing, boots from disks >2 TB, GUI interfaces)

VI. Parts: Random Access Memory (RAM)

  1. Memory types
    1. Static RAM (SRAM)
      1. Very fast, expensive memory used as cache on processors (typically 2-6 MB)
      2. https://en.wikipedia.org/wiki/Static_random-access_memory
    2. Dynamic RAM (DRAM)
      1. Standard memory in modern PCs on DRAM modules that are inserted into the motherboard
      2. https://en.wikipedia.org/wiki/Dynamic_random-access_memory
  2. DRAM Form
    1. Each DRAM module has multiple memory chips
    2. Dual inline memory module (DIMM) modules contain contacts on both sides of card to maximize pins
      1. DIMM is found on desktop computers, while SO-DIMM, Mini-DIMM and Micro-DIMM on smaller devices
      2. https://en.wikipedia.org/wiki/DIMM
    3. Memory may have heat spreader on back of module
    4. Single-sided SDRAM is one bank of memory that functions as a single unit (optimal)
      1. Single-sided is fastest, may actually have memory on both sides of module, and is all DIMM (dual pins)
      2. Double-sided SDRAM is two banks of memory and is slower than single-sided (parallel communication)
  3. DRAM Function
    1. Every BIT of memory stored on DRAM chip is physically represented by a capacitor and transistor
      1. Transistor acts as a gate, either allowing voltage to charge capacitor or not
      2. Capacitor holds either no charge (off=0) or 1.6 volts (on=1)
      3. https://en.wikipedia.org/wiki/Memory_cell_(binary)
    2. Periodically requires electrical pulse to refresh every 15 ms (charge capacitors)
      1. SDRAM is DRAM that has power refreshed synchronized with CPU cycles (standard memory type)
      2. https://en.wikipedia.org/wiki/Synchronous_dynamic_random-access_memory
    3. Error detection
      1. Parity checking has no error correction, so system may crash if error is detected
        1. On each memory chip, each byte (8 bits) uses one extra bit for error checking
        2. https://en.wikipedia.org/wiki/Parity_bit
      2. ECC RAM is error correcting and is used on servers (often combined with RDIMM - buffered RAM)
        1. https://en.wikipedia.org/wiki/ECC_memory
    4. DDR memory makes 2 transfers of data per cycle
      1. DDR3 (240 pin) is the current norm as of 2016 (faster than DDR, DDR2)
      2. DDR4 is available on higher end systems
      3. https://en.wikipedia.org/wiki/Double_data_rate
    5. Channels
      1. Memory modules communicate via channels to northbridge and CPU
      2. Single channel configurations connect all memory modules (e.g. 4) as one unit to CPU (slower)
      3. Dual, Triple or Quad Channels connect memory modules via multiple channels to the CPU (faster, standard)
        1. DRAM module slots may be color coded to indicate which modules are on the same channel
        2. In a quad channel configuration, each bank of 4 memory rows, has its own channel
      4. https://en.wikipedia.org/wiki/Multi-channel_memory_architecture
    6. Buffered RAM (Registered RAM, RDIMM)
      1. Helps keep system stable, but more expensive, and typically limited to servers (often combined with ECC)
      2. https://en.wikipedia.org/wiki/Registered_memory
  4. DRAM Specifications
    1. Module transfer rate is data transfer rate per clock cycle (MB/s) and appears in module type (e.g. PC2700 is 2667 MB/s)
    2. Bus speed is transactions/sec (MT/s) and appears in chip type (e.g. DDR333 is 333 MT/s)
    3. Column Address Strobe (CAS) Latency is delay in cycles from CPU instruction to RAM data delivery (lower is better)
    4. Timing refers to 4 different RAM latencies (lower is better for each)
    5. https://en.wikipedia.org/wiki/DDR3_SDRAM

VII. Parts: Power Supply Unit (PSU)

  1. Form factors
    1. ATX form factor for power is standard for desktop computers
    2. Flex ATX form factor for power is standard for server (typically with quick release for more rapid replacement)
  2. Wall current (AC) and dual voltage
    1. Wall socket current AC 110-120 (North, Central and part of South America) or AC 220-240 (remainder of world)
    2. Wall current is converted to DC via power supply unit (desktop) or power brick (laptop)
    3. Confirm on power supply that unit can accept AC 110 or 220 (may require flipping switch on desktop)
      1. Most modern devices are dual voltage (110 or 220) and can use either (with converter)
  3. Power specifications (DC)
    1. Power (watts) = Volts * Amps
    2. Volts (v) at 3.3, 5 or 12 volts DC, is the pressure of the electricity
    3. Current (amps) is flow rate of electricity
    4. Confirm that power supply has adequate wattage to power machine
      1. Power calculators can determine power needed for processor, fans, graphics cards, sound cards, hard drives...
      2. http://outervision.com/power-supply-calculator
  4. Power supply unit (PSU) connectors
    1. Removable connector cables are ideal
    2. Connectors include 20/24 pin ATX cable to motherboard, SATA power cable, 6/8 pin PCIe power cable
      1. Some devices (e.g. fans, IO) are powered off the motherboard pin slots
  5. Power supply unit (PSU) rails (inside the PSU)
    1. Single rail has one internal bus shared among all power connectors
      1. If computer needs to power down a device due to a problem, it powers down entire system
    2. Multi rail
      1. Computer can isolate power to a single device (shutting down only that device, stability functionality)
      2. No performance benefit to Multi-rail over single-rail
  6. Installation, Diagnostics and Maintenance
    1. Power supply tester devices are available
    2. Failed power supply
      1. Do NOT open power supply (risk of electrocution from high energy capacitors)
      2. Replace the entire power supply (typically straight forward if standard form factor, e.g. ATX)
  7. References
    1. https://en.wikipedia.org/wiki/Power_supply_unit_(computer)

VIII. Parts: Peripheral Component Interconnect (PCI) Card Slots

  1. Serial PCI-Express or PCIe (newer, current standard)
    1. Colored slots (black, green, yellow..), most peripheral cards, esp. graphics cards
    2. Fastest slots from 250 MB at 1x (1 data lane) to 32 GB/s for 16x (16 data lanes)
    3. https://en.wikipedia.org/wiki/PCI_Express
  2. Older expansion cards
    1. Conventional, Parallel PCI (older)
      1. Older, gray slots, relatively slow, from 133 MB/s for 32 bit to 533 MB/s for 64 bit
      2. https://en.wikipedia.org/wiki/Conventional_PCI
    2. PCI-X (older, server)
      1. Older 64-Bit server slot transmitting at 1 GB/s, and replaced by newer PCI-Express slots
      2. https://en.wikipedia.org/wiki/PCI-X
    3. Accelerated Graphics Port or AGP (older, brown slots)
      1. Older graphics card slots that transmitted at up to 2 GB/s
      2. https://en.wikipedia.org/wiki/Accelerated_Graphics_Port
  3. Riser Card
    1. Expansion cards that have slots for other PCI cards to be inserted in horizontal position (if vertical space is tight)
  4. Driver installation
    1. Vendor's driver is preferred over plug-and-play generic driver on the system
    2. May install, update drivers via device manager in windows (also available from computer management)

IX. Parts: Miscellaneous

  1. Storage
    1. See Computer Storage Device
    2. See Wired Connection Interface
  2. Output devices
    1. Computer Display
    2. Computer Printer
    3. Speakers
  3. Input devices
    1. Mouse (desktop) or Trackpad (notebook)
    2. Keyboard
    3. Game pads (or joy sticks)
    4. Touch pads or Touch Screens
      1. Operate on small electrical conduction (capacitive), not pressure, via touch or stylus
    5. Scanners
    6. Bar code readers (or QR Code readers)
    7. Authentication devices
      1. Biometric devices (e.g. fingerprint readers)
      2. Smart code readers
    8. Motion Sensors
    9. Digital imaging (digital cameras, digital video, webcams)
    10. Audio (microphone, MIDI)
    11. GPS transmitter
  4. Network
    1. See Computer Network
    2. Wireless Connection Interface
    3. Wired Connection Interface

X. Approach: Configuration

  1. See Computer Network
  2. Manufacturers
    1. Original Equipment Manufacturer (OEM, e.g. HP, Dell)
    2. Do-It Yourself Custom built machines (White box)
      1. Home (or business) assembly of ala carte parts
  3. Special cases with unique hardware requirements
    1. Graphics or CAD workstations
    2. Audio Video Editing
    3. Gaming Machine
    4. Home theater
    5. Home Server

XI. Differential Diagnosis: System/Motherboard Problems

  1. Unexpected Shutdown
    1. Under-powered supply (PSU) for installed device requirements (e.g power supply overheating)
    2. Electrical short (consider nearby conductors such as screws)
    3. Disrupted power cord
  2. System Lockup or freeze
    1. Software CPU intensive activities
    2. RAM errors (esp. if non-compatible RAM is installed)
    3. Under-powered supply (PSU) for installed device requirements (e.g power supply overheating)
  3. Power On Self Test (POST) Errors
    1. If errors occur, system generates distinctive "code beeps" on start-up self-test (POST)
    2. Machine will halt start-up and not boot after emitting a specific number of beeps (OEM specific)
    3. Indicates a hardware issue based on number of beeps
      1. Example problems: BIOS, RAM, Motherboard, CMOS battery, Video card, CPU
    4. System indicator lights may also given additional information
  4. Repeated Re-booting before user can log-on
    1. Under-powered supply (PSU) for installed device requirements (e.g power supply overheating)
    2. Disconnected power supply unit cable to motherboard or device
    3. Device driver resource conflict (e.g. video card)
  5. No Power
    1. Confirm computer is plugged into a working electricity receptacle
    2. Power supply set to incorrect voltage (e.g. 110 instead of 220 or vice versa)
  6. Power only to one device (e.g. fans) but not to others
    1. Disconnected Molex connector to hard drives or other devices
    2. Disconnected motherboard power connector
  7. Smoke or burning smell
    1. Fire risk (unplug immediately)
    2. Power supply failure
    3. Capacitor failure
    4. Electrostatic component damage
  8. System overheating
    1. System Fan failure (check power to fans)
    2. Video card fan failure
    3. Inadequate ventilation
      1. Ventilation ports blocked
      2. Blow all dust from within computer case with compressed air
  9. Noisy Machine
    1. Noisy Mechanical Hard Drive
    2. Optical drive start-up (or optical disks may become stuck and prevent spinning)
    3. Liquid-cooled machines
    4. Loud, squeeky fan (consider removing from case, oiling and replacing)
  10. Blue Screen of Death (and other proprietary crash screens)
    1. Cause of failure is often dumped to screen (screen capture the error codes, e.g. take picture)
    2. Device driver conflict
    3. RAM memory incompatibility

XII. Differential Diagnosis: BIOS Problems

  1. BIOS Time/date falls behind, resets or prolongs Power On Self Test (POST)
    1. CMOS Battery Failure
    2. BIOS Misconfiguration (can reset to factory default)
  2. System Booting from incorrect device, will not boot or operating system not found
    1. BIOS boot order misconfigured
    2. Boot-up device left connected (e.g. USB or optical disk)
    3. Corrupted CMOS chip (requires a motherboard replacement)
  3. Management
    1. Correct UEFI/BIOS settings (or reset to factory default)

XIII. Differential Diagnosis: Peripheral Problems

  1. Intermittent device failure
    1. Unplug and re-plug the offending device into its port (e.g. USB)
    2. Check connected and adequate power supply

XIV. References

  1. Warner (2015) CompTIA A+, Pluralsight

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