Power
The power supply converts incoming AC power into regulated DC outputs used by computer hardware. Motherboard voltage-regulation circuitry then provides the voltages required by specific components.
CompTIA A+ • Mission 02
Inside the Machine
Before you replace or upgrade computer parts, understand what the parts do together. Investigate power, data, the motherboard, CPU, RAM, storage, bits and bytes, and safe hardware handling.
A+ quick navigation
Mission briefing
Power makes the hardware work. Data gives it something to work on.
A computer uses electrical power and electrical signaling, but those ideas are not interchangeable. In this mission you will connect the physical machine to the bits, bytes, files, and speeds you see in A+.
Data
Digital hardware represents information with binary states. A bit is a 0 or 1. Hardware detects valid LOW and HIGH voltage ranges as logic states; the exact thresholds depend on the device and its electrical specification.
1. Power is not data
Which statement is most accurate?
A bit is information: 0 or 1. Digital circuits use physical states, commonly voltage ranges, to represent those values. A bit is not a unit of electrical power.
A+ connection
Core 1 hardware study includes power supplies, motherboards, CPUs, RAM, storage, connectors, and safe technician tools. Understanding their roles makes hardware installation and troubleshooting questions easier to reason through.
2. Follow the power
Use this simplified model. After the PSU and motherboard, power is distributed to multiple components; it does not have to pass through the CPU before reaching RAM or storage.
Wall AC→Power supply→Motherboard / regulators→CPU • RAM • storage • cards • fans
Voltage (V)
Electrical potential difference. PC power supplies commonly provide 12 V, 5 V, and 3.3 V DC rails, while onboard regulators create additional voltages needed by components.
Current (A)
Rate of electric charge flow. A device draws current according to the work it is doing and its electrical design.
Power (W)
Rate of energy use. For a DC load, power relates to voltage and current: watts = volts × amps.
Logic levels
Do not memorize one universal voltage for binary 0 and 1. Valid LOW/HIGH thresholds vary by technology, supply voltage, and component datasheet.
3. Meet the motherboard
The motherboard connects the components and provides pathways for power, data, and control signals.
CPU socket
Holds a compatible processor and provides electrical connections between the CPU and motherboard.
DIMM slots
Hold system RAM. Motherboard and CPU specifications determine supported memory type, capacity, speed, and channel configuration.
PCIe slots
High-speed expansion connections for devices such as graphics, network, storage, and other adapter cards.
Storage connections
SATA connects many drives and optical devices. M.2 slots can support devices such as NVMe SSDs depending on the motherboard.
4. CPU, RAM, and storage: different jobs
CPU — process
Executes instructions and performs calculations. Clock rate, cores, cache, architecture, workload, and other factors affect performance.
RAM — active workspace
Fast, volatile working memory used for data and instructions needed by running processes. Its contents are lost when power is removed.
Storage — keep it
Nonvolatile storage keeps files when power is off. Common A+ examples include HDDs, SATA SSDs, and NVMe SSDs.
Example: open a saved picture
Storage→RAM→CPU→graphics/display
This is a teaching model. Modern systems can use caching, DMA, integrated graphics, and other optimizations, so real data paths can be more complex.
A program is open and actively using data. Where is much of that working data kept temporarily?
RAM is the system's fast, temporary working area for active programs and data.
5. Bits become bytes — and bytes become files
A bit stores one binary value. Eight bits form one byte. Bytes are grouped into larger units used to describe file and storage capacity.
01000001
8 bits = 1 byte. In ASCII, this byte represents the capital letter A. Text encodings such as Unicode can require different numbers of bytes for different characters.
bit→8 bits = byte→KB→MB→GB→TB
Capacity
Storage and memory capacity are commonly described in bytes and larger byte-based units: MB, GB, TB.
Transfer rate
Network speeds are commonly stated in bits per second: Mb/s or Gb/s. File-copy speeds may be shown in bytes per second: MB/s or GB/s.
Why does capitalization matter in speed labels?
b = bit and B = byte. Because 8 bits make 1 byte, 800 Mb/s is a theoretical 100 MB/s before accounting for protocol overhead and other real-world limits.
6. Safe hardware handling
ESD
Electrostatic discharge can damage sensitive electronics. Use appropriate ESD controls and handle components by their edges when possible.
Power safety
Shut down and disconnect equipment before internal service when appropriate. Do not open a power supply enclosure; hazardous energy can remain inside.
Which is the best practice before installing RAM in a desktop?
Protect both yourself and the hardware: follow shutdown/power procedures, use ESD precautions, and avoid touching contacts or chips unnecessarily.
7. Put the pieces together
A computer powers on, but opening several applications causes severe slowdown. Storage is healthy and the system has very little available memory. What component should you investigate first?
The evidence points toward memory pressure. A technician should verify RAM capacity, utilization, compatibility, and upgrade options before replacing unrelated hardware.
Knowledge check: 0 / 5 complete
Mission complete. You connected electrical power, logic states, bits/bytes, motherboard pathways, CPU, RAM, storage, and safe hardware handling. Keep the notebook pieces: later missions will build on them.
Certification alignment & educational notice
This independent FamilyPD activity supports study of CompTIA A+ Core 1 hardware concepts, including motherboards, RAM, storage, power supplies, CPUs, connectors, tools, and hardware troubleshooting. It is a study aid, not an official CompTIA course or exam.
CompTIA and A+ are trademarks of CompTIA, Inc. Family Personal Development, Inc. is not affiliated with or endorsed by CompTIA unless expressly stated. Certification requirements and objectives can change; learners should compare study materials with the current official CompTIA exam objectives.
Next: Return to the A+ Learning Path and continue building your notebook as new missions are released.