Skip to content
cyber journey
Code (2nd ed.)Help DeskTryHackMeA+ Core 1The Linux Command LineLearn Windows PowerShellNetworking for Sysadmins
§1§2§3§4§5§6

Resource Cheatsheet

Help Desk: Desktop Computer Components and Repair

TCM Practical Help Desk section 4 — ESD, CPU, RAM, drives, PSU, GPU, motherboard, ports and peripherals, POST and the BIOS, plus commands to inspect hardware.

Updated
Reading time
7 min read
Detail
Help Desk
Detail
§4
On this page

In one line: know what each part does, how it fails and how to swap it safely — then check it from the command line before you ever open the case.

Companion to: TCM Security, Practical Help Desk, section 4. Exam-level detail is in A+ Core 1 domain 3.

ESD and opening the case

  1. Shut down, switch off at the PSU, and unplug.
  2. Hold the power button for a few seconds to drain residual charge.
  3. Wear an antistatic wrist strap clipped to bare chassis metal; work on an antistatic mat.
  4. Handle cards and modules by the edges. Store parts in antistatic bags.
  5. Never open a PSU. Its capacitors hold a dangerous charge after unplugging.
  6. Photograph cable layouts before disconnecting anything.

Components at a glance

Part Job Common failure signs
CPU Executes instructions Overheating shutdowns, no POST
RAM Short-term working memory (volatile) Random crashes, blue screens, beep codes, no POST
Drive Long-term storage Clicking, slow boots, “no boot device”, SMART warnings
PSU AC mains → DC rails Dead system, random reboots, burning smell
GPU Display output and graphics processing No display, artefacts, driver crashes
Motherboard Connects everything No POST, dead ports, swollen capacitors

CPU

  • Specs: cores, threads, clock speed (GHz) and cache.
  • Platforms: Intel and AMD use different sockets — the CPU must match the board’s socket and chipset.
  • Install:
    1. Lift the socket lever and align the triangle marker (pin 1). No force.
    2. Close the lever.
    3. Add a pea-sized dot of thermal paste.
    4. Seat the cooler with even pressure.
    5. Plug the cooler into the CPU_FAN header.
  • Replacing the cooler: clean off old paste with isopropyl alcohol and apply fresh.

RAM

  • Type: DIMMs for desktops. DDR generations are keyed differently and aren’t interchangeable.
  • Install: open the clips, line up the notch, and press evenly until both clips snap.
  • Dual channel: use matched modules in the manual’s recommended slots (often A2 + B2).

Drives

Type Connects via Notes
HDD 3.5” SATA data + SATA power Moving parts; don’t knock it while it runs
SATA SSD 2.5” SATA data + SATA power About 550 MB/s ceiling
NVMe M.2 M.2 slot, held by a standoff screw Several GB/s; check the slot supports NVMe

PSU

  • Wattage: size for peak load plus headroom.
  • Efficiency: 80 PLUS ratings, in order: White → Bronze → Silver → Gold → Platinum → Titanium.
  • Connectors:
    • 24-pin to the motherboard
    • 4/8-pin to the CPU
    • 6/8-pin or 16-pin (12V-2x6) to the GPU
    • SATA power to drives
  • Checking it: use a PSU tester rather than guessing.

GPU

  • Integrated vs dedicated: integrated graphics live in the CPU; a dedicated card sits in the PCIe x16 slot.
  • Power: higher-end cards need supplemental PCIe power cables.
  • Classic ticket: “no display” after fitting a graphics card — the monitor is still plugged into the motherboard’s video port instead of the card.

Motherboard

  • Form factors: ATX > microATX > Mini-ITX. Mount on standoffs so the board never touches the case.
  • Key parts: chipset, CPU socket, RAM slots, PCIe slots, M.2 slots, SATA ports, and the CMOS battery (CR2032).
  • Headers:
    • Front panel: power switch, reset switch, power LED +/−, drive LED +/−
    • USB and audio
    • Fans

Ports, cables and peripherals

Port Notes
USB-A / USB-C Peripherals, storage, charging; USB-C is reversible
HDMI / DisplayPort Digital video and audio
DVI / VGA Older video; VGA is analog
RJ45 Ethernet
3.5 mm audio Green = output, pink = microphone, blue = line in
PS/2 (legacy) Purple = keyboard, green = mouse

POST and the BIOS

Step What happens
1. Power on PSU stabilises, then signals “power good”
2. POST Firmware checks CPU, RAM and video
3. Beep / LED codes Report failures — vendor-specific, so check the manual. Many boards have CPU / DRAM / VGA / BOOT debug LEDs
4. Boot device Firmware follows the boot order to find a bootloader
  • Setup keys: usually Del or F2; the boot menu is often F12, F11 or Esc.
  • Clear CMOS to reset firmware settings: use the jumper, or remove the coin cell for a few minutes with the PC unplugged.
  • BIOS vs UEFI: UEFI is the modern replacement — GPT disks, Secure Boot, graphical setup.

Troubleshooting a ticket

The CompTIA method, as used for Ticket Interrupts:

  1. Identify the problem — question the user, reproduce it, note recent changes.
  2. Establish a theory of probable cause — start with the obvious.
  3. Test the theory — if it’s wrong, go back to step 2 or escalate.
  4. Plan and implement the fix.
  5. Verify everything works, and prevent it happening again.
  6. Document findings, actions and outcome in the ticket.

Inspect hardware without opening the case

Want Windows (PowerShell) Linux
CPU Get-CimInstance Win32_Processor | Select-Object Name, NumberOfCores, NumberOfLogicalProcessors, MaxClockSpeed lscpu
RAM modules Get-CimInstance Win32_PhysicalMemory | Select-Object BankLabel, Capacity, Speed, Manufacturer free -h · sudo dmidecode -t memory
Drives and health Get-PhysicalDisk | Select-Object FriendlyName, MediaType, BusType, Size, HealthStatus lsblk · sudo smartctl -a /dev/sda
GPU Get-CimInstance Win32_VideoController | Select-Object Name, DriverVersion lspci | grep -iE 'vga|3d'
Motherboard Get-CimInstance Win32_BaseBoard | Select-Object Manufacturer, Product sudo dmidecode -t baseboard
BIOS version Get-CimInstance Win32_BIOS | Select-Object SMBIOSBIOSVersion, ReleaseDate sudo dmidecode -t bios
Everything msinfo32 · dxdiag sudo lshw -short
USB devices Get-PnpDevice -Class USB lsusb

wmic is deprecated — use Get-CimInstance. smartctl comes from the smartmontools package.

🔐 Security notes

  • Physical access beats most software security. Anyone with the case open or a USB boot stick can reset passwords offline or pull the drive.
    • Countermeasures: a firmware password, Secure Boot, USB boot disabled, and full-disk encryption (BitLocker).
  • Hardware keyloggers sit inline between the keyboard and the USB port. Glance at the back of shared or public PCs.
  • Old drives hold data. Wipe or destroy drives you replace before disposal — deleting files isn’t enough.
  • Firmware matters. BIOS/UEFI updates fix security flaws, so apply them from the vendor only.

Practice drills

1. A PC powers on, fans spin, but there's no display and three beeps. First step?

Look up that beep code in the motherboard manual. It’s vendor-specific, and often points at RAM — reseat the modules.

2. Confirm how much RAM is installed, and in which slots, without opening the case.

Get-CimInstance Win32_PhysicalMemory | Select-Object BankLabel, Capacity, Speed

3. A new graphics card shows "no signal". Most likely cause?

The monitor is plugged into the motherboard’s video output, not the card’s.

4. The clock resets to 2009 every boot. What part?

The CMOS battery (CR2032).

5. Is the drive SSD or HDD, and is it healthy?

Get-PhysicalDisk | Select-Object FriendlyName, MediaType, HealthStatus

Key takeaways

  • Unplug, drain, strap on. Never open a PSU.
  • CPU, RAM, drives, PSU, GPU and motherboard each have tell-tale failure signs — learn them.
  • POST beep and LED codes are vendor-specific; the clear-CMOS jumper resets firmware settings.
  • Diagnose from the OS first: Get-CimInstance, Get-PhysicalDisk, msinfo32; lscpu, lsblk, dmidecode.
  • Physical access defeats software security — firmware passwords and BitLocker close that gap.

Search

Filter by collection