3.14 Power Supplies

10) A computer's power supply converts main AC to low-voltage regulated DC power for the internal components. You are building a new computer, and you are deciding which type of power supply to install. Which of the following definitions BEST describes a valid type of power supply? - A single-rail power supply provides one rail (PCB trace) to always provide equal wattage to all the devices attached to the power supply. - A dual-rail power supply provides separate rails (PCB traces) to provide equal wattage to the devices attached to each rail. - A single-rail power supply provides one rail (PCB trace) to provide the best safety mechanism for the computer by having a single point of shutdown in the event of a short circuit. - A dual-rail power supply provides separate rails (PCB traces) to balance the power load between multiple circuits (this prevents any one circuit from becoming overloaded).

- A dual-rail power supply provides separate rails (PCB traces) to balance the power load between multiple circuits (this prevents any one circuit from becoming overloaded).

9) Your company relocated you from the United States to their United Kingdom office in London. You brought your personal computer with you, and you are in the process of setting it up. Your computer was previously configured to receive 115 VAC, but the electricity in London uses 230 VAC. Which of the following would allow your computer to run on 230 VAC? - Purchase a new power supply that is compatible with 230 VAC. - Inspect the power supply unit for a manual voltage switch and move it to 230 VAC. Otherwise, no action is necessary. - Purchase a voltage converter and plug your computer into the converter box. - Edit the BIOS and modify the voltage input setting.

- Inspect the power supply unit for a manual voltage switch and move it to 230 VAC. Otherwise, no action is necessary.

8) You need to replace the power supply in your home desktop computer. Which of the following specifications are the MOST likely to affect your power supply choice? (Select three.) - Output wattage - Form factor - A fan that cools the unit - Input voltage selections - Type and number of connectors - Output voltage selections - An on/off power switch

- Output wattage - Form factor - Type and number of connectors

6) Which of the following components converts AC power to DC power? - Power supply - Surge protector - Voltage regulator - Capacitor

- Power supply

7) You are servicing a client's computer that has been randomly restarting. You decide to test the power supply voltage on the 12 V rail using a multimeter. Which of the following BEST describes the action you should take based on the multimeter reading shown below? - Switch the voltage selector on the back of the power supply to 230 volts AC. - Replace the power supply because it is failing. - Continue using the power supply until the voltage drops to less than 9 volts. - Keep using the power supply, but stop using that 12 V rail.

- Replace the power supply because it is failing.

5) You are building a high-performance gaming PC with a modern multi-core processor. Which of the following statements about the 8-pin EPS12V connector is correct? - The 8-pin EPS12V connector is not necessary for modern multi-core processors. - The 8-pin EPS12V connector is used to provide power to the video card. - The 8-pin EPS12V connector is used to power SATA devices. - The 8-pin EPS12V connector provides four lines of 12 V power to the CPU.

- The 8-pin EPS12V connector provides four lines of 12 V power to the CPU.

1) You have a desktop computer that provides a 250-watt power supply. You recently added a four-disk RAID 10 array to the system, and now it spontaneously shuts down. Which of the following would MOST likely solve this issue? - Use the switch on the power supply to switch from 115 VAC to 230 VAC. - Upgrade to a power supply that provides more volts. - Upgrade to a power supply that provides more watts. - Upgrade to smaller capacity hard drives.

- Upgrade to a power supply that provides more watts.

3) Which of the following connectors provides additional power to the CPU from an ATX power supply using the fewest pins? (Select the correct connector.)

A

Alternating current (AC) power

AC is the type of current distributed through wall sockets. The voltage alternates between a negative and a positive charge. AC power is good for appliances requiring a high current.

4) You have just installed a new video card in your desktop computer for gaming purposes. Which of the following power supply connectors is designed to provide additional dedicated power to your new video card? (Select the correct connector.)

C

2) You have just installed a new hard drive in your desktop computer. Which of the following power supply connectors is designed to provide power to your new hard drive? (Select the correct connector.)

D

Direct current (DC) power

DC is the type of current used inside a computer. Negative particles are drawn toward a positive charge, creating a unidirectional current flow. This type of predictable, reliable current is ideal for components that require a lower current.

8-pin Entry-Level Power Supply 12 volt (EPS12V) CPU power

Modern processors consume even more power. The 8-pin EPS12V connector provides four lines of 12 V power. The 8-pin EPS12V was originally used with some older dual processor systems. All modern multi-core processors use this connector. Some power supplies have two 4-pin connectors (4+4) that are meant to be used side-by-side in the 8-pin plug.

Modular power supply

Modular power supply units come with a wide variety of detached cables. None of the cables are permanently attached. - The user attaches the cables needed for the specific computer. - This allows for better airflow, customization, and significantly less build clutter.

6+2-pin Peripheral Component Interconnect Express (PCIe)

Newer video cards require more power than can be supplied through the PCIe bus. The 6+2-pin PCIe connector plugs directly into the video card to supply additional, dedicated power. The 6+2-pin PCIe: - Provides up to 150 watts - Is also known as a PCI Express Graphics 6+2 pin (PEG6+2) Some motherboards have only a 6-pin PCIe connector. These connectors provide up to 75 watts.

Power supply

Power supplies are responsible for powering every component in a computer system. Power supplies perform the following functions: - Convert alternating (AC) power to direct current (DC) power. - Provide components with the correct levels of DC voltage. - Aid in thermal management.

Redundant power supply

Redundant power supplies are generally found in servers and other network devices. A redundant power supply is hot swappable. This allows a bad power supply to be removed without shutting the server or device off. It can be replaced the same way. This redundancy keeps critical servers running even if one power supply dies.

Advanced Technology Extended (ATX) power supply

Standard Advanced Technology eXtended (ATX) power supplies provide + 3.3 volts, +/- 5 volts, and +/- 12 volts of DC power. Most modern components require +12 volt output. ATX power supplies provide soft power. This means even when the computer is turned off, the motherboard has power. Soft power allows the computer to be turned on and off by the operating system or over the network.

4-pin 12 V Pentium 4 (P4) power

Starting with the P4 processor, CPUs required more power than could be provided through the ATX power plug. The 4-pin 12 V connector: - Connects to the motherboard. - Provides two dedicated 12 V wires to the CPU. (Older processors used only 5 V power.) The 4-pin 12 V CPU connector is not the same as the 20+4-pin ATX power connector.

24-pin (20+4 pin) ATX connector

The 24-pin ATX power plug supplies power to the motherboard. Some 24-pin connectors have one 20-pin plug and a detachable 4-pin plug. - This allows for backwards compatibility with 20-pin motherboards. - You can plug a 24-pin ATX power plug into a 20-pin motherboard connector, leaving the four pins unconnected. Older motherboards used 20-pin power plugs. With a 24-pin ATX power plug, the four extra pins supply an additional 3.3, 5, and 12 volts of DC power.

4-pin mini-Molex

The 4-pin mini-Molex connector provides both 5 and 12 volts and is used by floppy drives. Most modern power supplies do not have a 4-pin mini-Molex connector.

4-pin peripheral power

The 4-pin peripheral power connector (colloquially called a 4-pin Molex connector) is used by legacy components (e.g., Integrated Drive Electronics (IDE) hard drives and Parallel Advanced Technology Attachment (PATA) optical drives), case fans, and other accessory devices. The connector provides both 5 V (red wire) and 12 V (yellow wire). Each power supply cable typically has multiple 4-pin connectors on the same cable. When connecting devices, try to balance the devices connected to each cable.

Serial ATA (SATA) power

The SATA power connector has 15 pins and provides 3.3, 5, and 12 volts. As its name implies, it powers SATA devices. You can use a special adapter to convert a 4-pin peripheral power connector to a SATA connector. When using an adapter, or on some power supplies, the connector supplies only 5 and 12 volts.

230 volts

Used in Europe

100 volts

Used in Japan

115 volts

Used in North America

220 volts

Used in most parts of Asia