Power Supply Facts

Question 1

Power supplies performs what functions

Answer 1

• Convert AC power to DC power
• Provide components with the correct levels of DC
  voltage
• Aid in thermal management

Question 2

Standard ATX power supplies level

Answer 2

• +3.3 volts; +/- 5 volts; +/- 12 volts

* Modern components require + 12 volts

Question 3

Dual Rail Supplies

Answer 3

• 2 or more + 12 volts rails
• Separate rails balance the power load between
  multiple circuits, preventing any one circuit from
  becoming overloaded

Question 4

Power supplies Facts

Answer 4

• Should be matched to motherboard & case
• Has a voltage switch that toggles between 115 & 230
• Rated in watts
• ATX power supplies provide soft power

Question 5

24-pin (20+4 pin) ATX connector

Answer 5

• Supplies power to the motherboard
• Some have 20-pin plug and a detachable 4-pin plug
  allows for backwards compatibility with 20pin mb

Question 6

4-pin 12 V (P4) power

Answer 6

• Provides two dedicated 12 V wires to the CPU

* Not the same as the 20+4 pin ATX power connector

Question 7

8-pin EPS12V CPU power

Answer 7

• Provides 4 lines of 12 V power
• All modern multi-core processors use this connector
• Some have two 4-pin connectors which are meant
  to be used side by side

Question 8

6+2-pin PCIe

Answer 8

• Plugs directly into the video card to supply additional
  power
• Provides up to 150 watts
• AKA a PEG6+2 (PCI Express Graphics 6+2pin)
• Some motherboards only have a 6-pin PCIe
  connector – those provide up to 75 watts

Question 9

4-pin peripheral power

Answer 9

• aka 4-pin Molex connector used by legacy components (IDE hard drives & PATA optical drives)
• Provides both 5 V (red wire) & 12 V ( yellow wire)

Question 10

SATA power

Answer 10

• 15 Pin connector & provides 3.3, 5, 12 V

Question 11

4-pin mini-Molex

Answer 11

• Provides 5 and 12 volts & used by floppy drives

* Most modern power supplies don’t have this connector

Question 12

Symptoms of a bad power supply includes:

Answer 12

• Computer does not turn on
• Computer sporadically shuts off or reboots
• A broken or noisy fan

Question 13

Power supply levels

Answer 13

• Should be within +/- 5% of normal

Question 14

12 V rail level should be:

Answer 14

• Between 11.4 and 12.6 Volts

Question 15

5 V rail level should be:

Answer 15

• Between 4.7 and 5.25 Volts

Question 16

3.3 V rail level should be:

Answer 16

• Between 3.1 and 3.4 Volts