PSU(Power Supply Unit)

2. Power Supply Unit - The PSU (Power
Supply Unit) is an internal hardware
component used to supply the components
within the computer with power. Besides
properly supplying power to the computer
and all its internal components, the power
supply also converts the AC electrical
current found in most standard wall sockets
into a lower DC voltage that the computer
components use.

3. POWER SUPPLY UNIT

4. VARIOUS PC POWER SUPPLY CABLES AND CONNECTORS
ORIGINAL PC MAIN POWER CABLES
The original PC debuted in 1981 and used two cables to
connect the PSU (power supply) to the motherboard.

6. 4 PIN PERIPHERAL POWER CABLE(4 PIN MOLEX)
The four pin peripheral power cable dates back to the original PC. It was
used for floppy drives and hard disks. It's still around and is now also used
for all kinds of things including add-on fans, extra video card power,
supplemental motherboard power, and case lighting. It's as old as the hills
but is still very widely used.

7. Pinout
Pin number Wire color Description
1 yellow +12 volts
2 black ground
3 black ground
4 red +5 volts
4 PIN PERIPHERAL POWER CABLE(4 PIN MOLEX)

8. FLOPPY DRIVE POWER CABLE
Pinout
Pin number Wire color Description
1 red +5 volts
2 black ground
3 black ground
4 yellow +12 volts
Floppy cables are built
with small connectors
and 20 awg wire so they
are limited to relatively
low current uses.

9. 6 PIN AUXILIARY POWER CABLE
The aux power cable was added to provide extra wattage to
motherboards for 3.3 and 5 volts. This connector is rarely
used anymore. It's most commonly found on older dual CPU
AMD motherboards.

10. Pinout
Pin number Wire color Description
1 black ground
2 black ground
3 black ground
4 orange +3.3 volts
5 orange +3.3 volts
6 red +5 volts
6 PIN AUXILIARY POWER CABLE

11. SATA POWER CABLE
SATA was introduced to upgrade the ATA interface (also called
IDE) to a more advanced design. SATA includes both a data cable
and a power cable. The power cable replaces the old 4 pin
peripheral cable and adds support for 3.3 volts (if fully
implemented).

12. SATA POWER CABLE

13. ATX 20 PIN MAIN POWER CABLE
In 1996 PC makers started switching to the ATX
standard which defined a new 20 pin
motherboard power connector.

14. Pinout
Pins 1 through 10 Pins 11 through 20
Description Wire color Pin number Pin number Wire color Description
+3.3 volts orange 1 11 orange +3.3 volts
+3.3 volts orange 2 12 blue -12 volts
ground black 3 13 black ground
+5 volts red 4 14 green PS_ON#
ground black 5 15 black ground
+5 volts red 6 16 black ground
ground black 7 17 black ground
PWR_OK gray 8 18 white
-5 volts
(optional)
VSB +5 volts purple 9 19 red +5 volts
+12 volts yellow 10 20 red +5 volts
ATX 20 PIN MAIN POWER CABLE

15. ATX 24 PIN MAIN POWER CABLE
The 24 pin main power connector was added in ATX12V 2.0 to
provide extra power needed by PCI Express slots. The older 20
pin main power cable only has one 12 volt line. The new 24 pin
connector added one line apiece for ground, 3.3, 5, and 12
volts.

16. Pinout
Pins 1 through 12 Pins 13 through 24
Description Wire color Pin number Pin number Wire color Description
+3.3 volts orange 1 13 orange +3.3 volts
+3.3 volts orange 2 14 blue -12 volts
ground black 3 15 black ground
+5 volts red 4 16 green PS_ON#
ground black 5 17 black ground
+5 volts red 6 18 black ground
ground black 7 19 black ground
PWR_OK gray 8 20 white
-5 volts
(optional)
VSB +5 volts purple 9 21 red +5 volts
+12 volts yellow 10 22 red +5 volts
+12 volts yellow 11 23 red +5 volts
+3.3 volts orange 12 24 black ground

17. ATX 20+4 PIN MAIN POWER CABLE
Motherboards can come with either a 20 pin main power
connector or a 24 pin main power connector. Many power
supplies come with a 20+4 cable which is compatible with
both 20 and 24 pin motherboards.

18. 24-pin ATX power plug; pins 11, 12, 23 and 24
form a detachable separate four-pin plug,
making it backward compatible with 20-pin ATX
receptacles

19. 24-PIN ATX12V 2.X POWER SUPPLY CONNECTOR
Color Signal Pin Pin Signal Color
Orange +3.3 V 1 13
+3.3 V Orange
+3.3 V sense Brown
Orange +3.3 V 2 14 −12 V Blue
Black Ground 3 15 Ground Black
Red +5 V 4 16 Power on Green
Black Ground 5 17 Ground Black
Red +5 V 6 18 Ground Black
Black Ground 7 19 Ground Black
Grey Power good 8 20 Reserved None
Purple +5 V standby 9 21 +5 V Red
Yellow +12 V 10 22 +5 V Red
Yellow +12 V 11 23 +5 V Red
Orange +3.3 V 12 24 Ground Black
1.^ Jump up to: Light-blue background denotes control signals.
2.^ Jump up to: Light-green background denotes the pins present only in the 24-
pin connector.
3.Jump up^ In the 20-pin connector, pins 13–21 are numbered 11–20, respectively.
4.Jump up^ Supplies +3.3 V power and also has a second low-current wire for remote
sensing
5.Jump up^ A control signal that is pulled up to +5 V by the PSU, and must be driven
low to turn on the PSU.
6.Jump up^ A control signal that is low when other outputs have not yet reached, or
are about to leave, correct voltages.
7.Jump up^ Formerly −5 V ( white wire), absent in modern power supplies; it was
optional in ATX and ATX12V ver. 1.2, and deleted since ver. 1.3.

20. 4 PIN ATX +12 VOLT POWER CABLE
This cable added two more 12 volt lines so more of the load could be
shifted to 12 volts. The power coming from this connector is usually
used to power the CPU but some motherboards use it for other things
as well. The presense of this connector on a motherboard means it's an
ATX12V motherboard.

21. Pinout
Pins 1, 2 Pins 3, 4
Description Wire color Pin number Pin number Wire color Description
ground black 1 3 yellow +12 volts
ground black 2 4 yellow +12 volts
4 PIN ATX +12 VOLT POWER CABLE

22. 8 PIN EPS +12 VOLT POWER CABLE
This cable was originally created for workstations to provide 12
volts to power multiple CPUs. But as time has passed many
CPUs require more 12 volt power and the 8 pin 12 volt cable is
often used instead of a 4 pin 12 volt cable.

23. Pinout
Pins 1 through 4 Pins 5 through 8
Description Wire color
Pin
number
Pin
number
Wire color
Descriptio
n
ground black 1 5 yellow
+12 volts
(12V1)
ground black 2 6 yellow
+12 volts
(12V1)
ground black 3 7 yellow
+12 volts
(12V1 or
12V2)
ground black 4 8 yellow
+12 volts
(12V1 or
12V2)
8 PIN EPS +12 VOLT POWER CABLE

24. 4+4 PIN +12 VOLT POWER CABLE
Motherboards can
come with either a 4 pin
12 volt connector or
an 8 pin 12 volt
connector. Many power
supplies come with a
4+4 pin 12 volt cable
which is compatible
with both 4 and 8 pin
motherboards.

25. 6 PIN PCI EXPRESS POWER CABLE
This cable is used to provide extra 12 volt power to
PCI Express expansion cards.

26. Pinout
Pins 1 through 3 Pins 4 through 6
Description Wire color Pin number Pin number Wire color Description
+12 volts yellow 1 4 black ground
+12 volts or
not
connected
yellow or
not
connected
2 5 black ground
+12 volts yellow 3 6 black ground
6 PIN PCI EXPRESS POWER CABLE

27. 8 PIN PCI EXPRESS POWER CABLE
The PCI Express 2.0
specification released
in January 2007
added an 8 pin PCI
Express power cable.
It's just an 8 pin
version of the 6 Pin
PCI Express power
cable. Both are
primarily used to
provide supplemental
power to video cards.

28. Pinout
Pins 1 through 3 Pins 4 through 6
Description Wire color Pin number Pin number Wire color Description
+12 volts yellow 1 5 black ground
+12 volts yellow 2 6 black ground
+12 volts yellow 3 7 black ground
ground black 4 8 black ground
8 PIN PCI EXPRESS POWER CABLE

29. THANK YOU   