3.5 Given a scenario, install or replace the appropriate power supply

Question 1

Meaning of PSU?

Answer 1

Power Supply Unit

Question 2

What do PSUs do?

Answer 2

Supply low-voltage DC power to PC components

DC = Direct Current

Question 3

Why do PSUs contain a rectifier?

Answer 3

To convert AC power to DC power

(AC = Alternating Current) (DC = Direct Current)

Question 4

2 factors that determines the power supply’s compatiblity?

Answer 4

• Size
• Power connectors

Most PSUs designed for use with desktop PCs are based on the ATX form factor

Question 5

What voltage is typically used in North America?

Answer 5

120 VAC

Question 6

What voltage is typically used in the United Kingdom?

Answer 6

230 VAC

Question 7

What does it mean that most PSUs are dual voltage & auto-switching?

Answer 7

They can adapt to different input voltages automatically

Some PSUs feature a manual voltage switch; fixed types suit either low-line or high-line voltages. Clear voltage compatibility indication is crucial in PSUs and their documentation.

Question 8

What is the range of low-line VAC?

This would be used in regions like North America

Answer 8

100-127 VAC

Question 9

What is the range of high-line VAC?

This would be used in regions like teh United Kingdom

Answer 9

220-240 VAC

Question 10

What is power measured in?

Answer 10

Watts

Question 11

How is Watts calculated?

Answer 11

Voltage multiplied by current (V*I)

Question 12

What power output does a PSU need to power a PC?

Answer 12

Combined power requirements of the PC’s components

Question 13

What is the PSU’s output capability measured in?

Answer 13

Wattage rating

Question 14

What PSU rating is used for standard desktops?

Answer 14

200-300W

Question 15

What PSU rating is used for workstations & servers?

Answer 15

Over 300W

Due to meeting the demands of multiple CPUs, additional memory modules, disk drives, & tape units. Gaming PCs might require 500W or better power supplies to cope with the high specification CPU & graphics card(s)

Question 16

What does PSU efficiency refer to?

Answer 16

The measure of converting grid power to usable PC Power

The higher the percentage the better

If a PSU operates at 75% efficiency, it draws more power from the outlet than its output. The extra energy is lost as heat. With rising energy costs and environmental concerns, selecting an efficient PSU is crucial. ENERGY STAR 80 PLUS compliant PSUs must maintain 80% efficiency across load levels.

Question 17

3 voltages that PSUs supply to components?

Answer 17

• 3.3V
• 5
• 12V

Not all components use power at precisely these voltages. Voltage regulators are used to correct the voltage supplied form the PSU to the voltage required by the component.

Question 18

How is a modular PSU unique to other PSUs?

Answer 18

Has detachable power connector cables

Question 19

What systems mainly use redundant power supplies?

Answer 19

Servers

Question 20

What is required to use redundant power supplies?

Answer 20

Compatible motherboard