Know the port, the pin count, and the part that goes where.

Internal power connectors

The power supply feeds every internal component through a specific connector. The exam likes to ask which device uses which plug, and how many pins it has.

External devices like monitors and USB drives never plug into the internal PSU. A monitor has its own power cord; a USB drive gets power from the USB port or its own adapter.

USB versions, speed & power

USB is the most common interface for peripherals: keyboards, mice, printers, flash drives, external drives, webcams. Memorize the speed ladder — renamed versions make this a favorite exam topic.

The naming mess

Power

• USB 2.0 port: 500 mA at 5 V (2.5 W).
• USB 3.x port: 900 mA at 5 V (4.5 W).
• USB Power Delivery (USB-C): up to 100 W at 20 V / 5 A; PD 3.1 extends to 240 W at 48 V.
• A device that needs more than the port supplies needs an external power adapter.

Compatibility

USB is backward compatible, but a connection runs at the speed of the slowest part — port, cable, or device. A USB 2.0 drive in a USB 3.0 port works, at 480 Mbps. A device that requires 5 Gbps won't work properly on a USB 2.0 port.

Connector types

Type-A (flat host end), Type-B (square, printers), Mini-B and Micro-B (older phones, cameras), and Type-C (reversible, 24 pins, carries USB, Thunderbolt, DisplayPort alt mode, and PD power). Type-C is a connector shape, not a speed.

Thunderbolt

Thunderbolt's job is high-speed data plus multiple connection types through one port. It combines PCI Express data, DisplayPort video, and power delivery, and supports daisy-chaining up to 6 devices per port.

Video interfaces

DisplayPort uses a different signal format and connector than HDMI or DVI — they're not electrically equivalent. It works with them through adapters.

Adapters & converters

An adapter cable has a different connector on each end so devices with different interfaces can connect. It enables the connection — it never makes anything faster. The link runs at whatever the slower side supports.

Passive adapter vs. active converter

• Passive adapter: just rewires pins. Works only when both sides already speak the same signal (DVI-D ↔ HDMI are both digital; DVI-I ↔ VGA share the analog pins).
• Active converter: has a chip (and often needs USB power) to change the signal type, such as analog VGA ↔ digital HDMI.

Follow the signal

Name the adapter from source to destination: the device sending video is the first name, the display receiving it is the second. An old VGA computer feeding an HDMI projector needs a VGA-to-HDMI converter. A new HDMI laptop feeding an old VGA projector needs an HDMI-to-VGA converter.

Troubleshooting video connections

An intermittent "No Signal" on hardware that should be compatible points first at the physical layer: reseat the connectors, then swap in a known-good cable. Start with the simplest, cheapest fix before changing resolutions or connection types.

Storage interfaces

SATA revisions

SATA I = 1.5 Gbps, SATA II = 3 Gbps, SATA III = 6 Gbps. Each SATA port connects exactly one device, so four ports means four drives unless you add an expansion card or port multiplier.

Peripheral & legacy connectors

Why serial is "legacy": RS-232 tops out around 115 kbps, far slower than USB. It still works with modern operating systems through USB-to-serial adapters, so the reason is speed and limited features, not compatibility.

Display technologies

LCD panel types: twist, rotate, tilt

Other display components

• Digitizer: the touch-sensitive layer that converts touch or stylus input into digital data. A touchscreen needs one; a stylus is just an input tool used on it.
• Inverter: converts DC power to AC. Older laptop LCDs with CCFL backlights use one to power the backlight; a failed inverter or backlight gives a very dim screen that's visible with a flashlight. LED backlights don't need an inverter.
• Backlight: lights an LCD from behind (LED today, CCFL in older units).
• Webcam and microphone: usually built into the laptop lid, around the display.

Motherboards & form factors

The motherboard decides what the rest of the system can be: which CPUs fit, how much and what type of RAM, how many expansion cards, and which storage and ports are available. It doesn't set CPU speed on its own, and it won't accept just any CPU.

Mass storage

RAM is volatile: it loses everything at power-off. Mass storage (HDD, SSD, flash) is non-volatile, so it keeps the OS, applications, and files when the computer is turned off.

CPUs, sockets & cooling

A motherboard supports a limited range of CPUs because each CPU family needs a specific socket, chipset, and power delivery (VRM) design. An AMD CPU can never go in an Intel board.

A BIOS/UEFI update can add support for newer CPUs within the same socket — it can't make an incompatible socket work.

Cooling

• Thermal paste fills microscopic gaps between the CPU's heat spreader and the heat sink so heat moves across efficiently. Apply a small amount; clean off old paste with isopropyl alcohol before re-seating.
• Active cooling: heat sink + fan, or liquid cooling (pump, radiator).
• Passive cooling: heat sink with no fan — chipsets and low-power processors.
• Heat spreaders: metal covers on RAM modules.

Memory (RAM)

RAM is fast, temporary working storage for the data and instructions the CPU is using while the computer is on. It's volatile — everything in it is lost at power-off — which is why you also need mass storage.

Don't confuse RAM's job with others: the system clock synchronizes components, buses move data between the CPU and devices, and storage keeps data permanently.

Expansion buses & cards

PCIe replaced PCI, PCI-X, and AGP. Instead of a shared parallel bus, each PCIe device gets a point-to-point, serial, full-duplex link made of lanes. Slot sizes are x1, x4, x8, and x16; graphics cards use x16.

Each version doubles the one before, and PCIe is backward and forward compatible — cards run at the lower version's speed.

Expansion cards

• Video (graphics) card: generates output for monitors. Its parts: the GPU, a processor built to render 2-D and 3-D images (it decides frame rate in games); dedicated video memory (GDDR, up to 24 GB or more on high-end cards); and video ports (HDMI, DisplayPort). AMD and NVIDIA make discrete GPUs; Intel and AMD also build integrated graphics into CPUs.
• Capture card: takes video in (e.g., HDMI from a console or camera) to record or stream it.
• Sound card, NIC, storage controller: add audio, networking, or extra drive ports.

M.2

M.2 drives get both data and power through the slot — no SATA or Molex power cable needed. An M.2 slot can carry SATA or NVMe (PCIe) signaling depending on the board and drive; check the keying (M-key for NVMe, B+M for SATA) and the motherboard manual.

Building & disassembly

Motherboard installation parts

• Standoffs sit between the motherboard and the case, raising the board so its circuits can't touch the metal case and short out.
• I/O shield (faceplate) snaps into the back of the case around the motherboard's rear ports; install it before the board. It keeps out dust and helps with airflow and EMI.

Who supplies which connector

Disassembly best practices

• Photograph or diagram connector positions and orientation before unplugging anything — tiny labels and colors aren't reliable.
• Use an ESD strap or mat and keep the system unplugged.
• Keep screws organized by location.

Troubleshooting methodology

CompTIA's six steps, in order. Questions give you a scenario and ask what comes next.

1. Identify the problem. Gather information, question users, identify recent changes, back up data before making changes, check for environmental or infrastructure changes.
2. Establish a theory of probable cause. Question the obvious; research if needed.
3. Test the theory to determine the cause. If confirmed, move on. If not, form a new theory or escalate.
4. Establish a plan of action and implement the solution. Follow vendor instructions.
5. Verify full system functionality and, if applicable, implement preventive measures.
6. Document findings, actions, and outcomes.