3.5 – Power: Computer Power

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Questions and Answers

Why is it important to disconnect from the power source when working on a computer?

To comply with manufacturer’s warranty requirements.

To ensure that no power is stored in capacitors. (correct)

To prevent receiving a shock from the electrical ground. (correct)

To avoid damaging the computer components.

What type of current do computer motherboards and components primarily use?

Step-up Alternating Current (SAAC)

Alternating Current (AC)

High Voltage Direct Current (HVDC)

Direct Current (DC) (correct)

What is the main function of a computer's power supply?

To convert AC power to a wireless transmission.

To regulate temperature within the computer.

To convert AC power into DC power. (correct)

To store electrical energy for later use.

Which of the following voltage outputs is commonly provided by power supplies for computers?

3.3 volts (C) Signup and view all the answers

What does an ampere (amp) measure in electrical terms?

The rate of electrons passing a point in one second. (C) Signup and view all the answers

What is not a recommended practice when dealing with electrical systems?

Connecting your body to the electrical ground. (D) Signup and view all the answers

How is electricity analogous to water flow in a hose?

Current is similar to the pressure of the water. (C) Signup and view all the answers

Which type of power do computer power sources receive from the outlet?

Alternating Current (A) Signup and view all the answers

What is the formula for calculating the total number of watts used by an electrical device?

Watts = Volts * Amps (B) Signup and view all the answers

What type of current is commonly supplied by wall outlets in the US?

Alternating Current (AC) (A) Signup and view all the answers

What is the typical frequency of alternating current in the US?

60 Hertz (B) Signup and view all the answers

If a computer power supply has a switch, what purpose does it serve?

To switch between different voltages (C) Signup and view all the answers

What type of current is produced by a computer power supply?

Direct Current (DC) (D) Signup and view all the answers

Which voltage is typically required for modern motherboards?

+3.3 volts (B) Signup and view all the answers

What is the standby voltage and its abbreviation in power supplies?

Standby Voltage (SB) (B) Signup and view all the answers

Why is it critical not to connect a manually switched 120-volt power supply to a 230-volt power source?

It may lead to sparks and smoke. (A) Signup and view all the answers

What happens to the current flow in alternating current systems?

It reverses direction at a fixed interval. (A) Signup and view all the answers

What is the relationship between electrical potential, voltage, and ground?

Voltage compares electrical potential to ground. (B) Signup and view all the answers

What voltages are commonly associated with PCI Express adapters and fans?

+3.3 volts and +12 volts (B) Signup and view all the answers

Which term describes the current that doesn't alternate direction?

Direct Current (B) Signup and view all the answers

What can be measured using a multimeter in terms of electrical systems?

The voltage from an outlet (A) Signup and view all the answers

What is the maximum power output that the described power supply can support?

850 watts (C) Signup and view all the answers

Which voltage outputs are provided by the 24-pin connector to the motherboard?

3.3 volts, 5 volts, and 12 volts (C) Signup and view all the answers

How do modern power supplies differ from older ones in terms of connectors?

They have more pins in their connectors. (B) Signup and view all the answers

What happens if a power supply fails in a system with multiple power supplies?

The other power supply takes over the full load. (A) Signup and view all the answers

What is a benefit of using a modular power supply?

It allows for easy cable management and better airflow. (C) Signup and view all the answers

What should be considered when selecting a power supply for a system?

The wattage needed for components inside the system. (D) Signup and view all the answers

What is indicated by the keying in the power connectors?

It prevents errors in plug connections. (D) Signup and view all the answers

What does a hot-swappable power supply allow you to do?

Replace it without powering down the system. (C) Signup and view all the answers

What is a common misconception regarding purchasing high-wattage power supplies?

Higher wattage ensures better system performance. (A) Signup and view all the answers

How can one determine the proper size for a power supply?

By calculating the total wattage needed for the system. (A) Signup and view all the answers

What does the clip on the 24-pin connector do?

It locks the connector into place securely. (B) Signup and view all the answers

In what scenario would you find multiple power supplies utilized?

In data centers or servers for load balancing. (B) Signup and view all the answers

What is a recommended approach for calculating power supply needs?

Double the calculated wattage for a good margin. (D) Signup and view all the answers

What physical feature distinguishes a hybrid power supply?

It combines fixed and modular wiring for flexibility. (D) Signup and view all the answers

Study Notes

Computer Power Supply Fundamentals

Safety First: Always disconnect your computer from the power source when working on it. Never connect yourself to the electrical system or ground. Capacitors in components can still hold a charge. Follow the manufacturer's instructions for discharging them.

Types of Power

Alternating Current (AC): The power from the wall outlet. Its direction constantly changes. Measured in voltage (V) and hertz (Hz), frequency of change. Standard voltages and frequencies vary by region (e.g., 110-120V/60Hz in US, 220-240V/50Hz in Europe).
Direct Current (DC): The power output by the computer's power supply. Flows in one direction. Measured in voltage (V).

Power Supply Components

Power Supply Unit (PSU): Converts AC to DC power. Crucial component; if it fails, the entire system will malfunction. Provides multiple DC voltages for different components (e.g., 3.3V, 5V, 12V).
Watts (W): A measure of power—calculated by multiplying volts (V) by amperes (A). Power supplies are rated by watts.
Amperes (A): A measure of the rate of electron flow. A higher amperage indicates a higher rate of electrical current flow, which is similar to a wider water hose that can carry more water.
Voltage (V): Electrical "force" pushing current through. Increasing/decreasing voltage is akin to turning on/off a faucet to increase/decrease the water flow.

Power Supply Choices

Voltage Switching: Some power supplies have a switch on the back to accommodate different regional voltages (120V or 230V). Auto-switching power supplies automatically adjust.
Modular Power Supplies: Provide separate cables for different components. Offers flexibility and reduces cable clutter, better airflow
Power Supply Sizing: Consider future upgrades when choosing a power supply. Doubling the wattage needed for your current needs is a good starting point.
Power Connections: The 24-pin connector is the primary connector for motherboard power. Older systems have a 20-pin connector.
Power Distribution: In servers or data centers, multiple power supplies can be used. Power supplies are frequently hot-swappable, allowing easy replacement without shutting down the system.

DC Voltages

Positive and Negative Voltages: DC voltages can be positive or negative (e.g., +5V, -12V). This indicates the potential difference relative to ground.
Voltage Usage: Different components have different power requirements. Higher voltages like +12V are often for components needing more power (e.g., video cards, hard drives).

Additional Details

Standby Voltage (+5V SB): Used to maintain a low power state for hibernation mode.

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Description

Test your knowledge on computer power supply fundamentals, including types of power and essential safety precautions. This quiz covers key concepts such as AC and DC power, the role of the Power Supply Unit (PSU), and important measurements like watts. Perfect for anyone looking to deepen their understanding of computer hardware.