Motherboard power Connectors

Every pc power supply has special connectors that attach to the motherboard,giving strength to the device processor, memory, and all slotted add-on boards(ISA, PCI, AGP). Attaching this connectors improperly deserve to have a devastatingeffect on her PC, including burning up both your power supply and also motherboard.The following sections information the motherboard strength connectors supplied by variouspower supplies.

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AT power Supply Connectors

Industry conventional PC, XT, AT, Baby-AT, and LPX motherboards all use the same type of key power supply connectors. These supplies feature two key power connectors (P8 and also P9), each v 6 pins that connect the power supply to the motherboard. Every standard pc power supplies that use the P8 and P9 connectors have them installed end to finish so the the 2 black wires (ground connections) top top both power cables are alongside each other. Part power supplies have them labeled together P1/P2 instead. Since these connectors usually have actually a clasp that avoids them from being inserted backward on the pins ~ above the motherboards, the major concern is getting the 2 connectors in the correct orientation next by side and also not absent a pin balance out on either side. Complying with the black-to-black dominion keeps you safe. You should take care, however, come make certain that no staying unconnected motherboard pins exist between or top top either next of the two connectors after you install them. A properly installed connector connects to and also covers every motherboard power pin. If any type of power pins are showing on either next of the connectors, the entire connector assembly is set up incorrectly, which can an outcome in catastrophic fail for the motherboard and everything plugged into it at the time of power-up. Number 3.6 mirrors the P8 and also P9 connectors (sometimes also called P1/P2) in their proper orientations once connecting.

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Figure 3.6 The P8/P9 strength connectors (sometimes additionally called P1/P2) that connect an AT/LPX power supply to the motherboard.

ATX main Power Connector

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Figure 3.7 ATX style 20-pin motherboard key power connector, perspective view.

Figure 3.8 reflects a view of the connector as if you were looking at it dealing with the terminal side.

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Figure 3.8 ATX/NLX 20-pin main power connector, terminal next view.

Table 3.3 ATX main Power it is provided Connector Pinout (Wire SideView)

Color

Signal

Pin

Pin

Signal

Color

Orange*

+3.3V

11

1

+3.3V

Orange

Blue

–12V

12

2

+3.3V

Orange

Black

GND

13

3

GND

Black

Green

PS_On

14

4

+5V

Red

Black

GND

15

5

GND

Black

Black

GND

16

6

+5V

Red

Black

GND

17

7

GND

Black

White

–5V

18

8

Power_Good

Gray

Red

+5V

19

9

+5VSB (Standby)

Purple

Red

+5V

20

10

+12V

Yellow

*Might have a 2nd orange or brown wire, provided for +3.3vsense feedback—used by the power supply to screen 3.3v regulation.


NOTE

The ATX supply features several voltages and signals not viewed before, such asthe +3.3v, PS_On, and also +5v_Standby. Therefore, adapting a typical LPX formfactor supply to do it work-related properly in an ATX system, is difficult—ifnot impossible—even though the shapes of the power offers themselves arevirtually identical.

However, due to the fact that ATX is a superset that the older in ~ standard, you deserve to use anadapter to allow an ATX power supply to affix to an larger Baby-AT stylemotherboard. Computer Power and Cooling (see the vendor list) sells this kind ofadapter.


ATX Auxiliary strength Connector

As motherboards and also processors evolved, the require for power came to be greater. Inparticular, chipsets and DIMMs to be designed to run on 3.3v, boosting thecurrent demand at that voltage. In addition, most boards included CPU voltageregulators draft to transform +5v power right into the unique voltage level requiredby the processors the board supported. Eventually, the high present demands onthe +3.3v and also +5v outputs to be proving too much for the number and also gauge the thewires used. Melted connectors were becoming more and an ext common as these wiresoverheated under this loads.

Finally, Intel modified the ATX specification to add a 2nd power connectorfor ATX motherboards and also supplies. The criteria was the if the motherboardneeded much more than 18A that +3.3v power, or much more than 24A of +5v power, an auxiliaryconnector would certainly be identified to lug the added load. These greater levels ofpower room normally necessary in equipment using 250-watt to 300-watt or greatersupplies.

This is a 6-pin Molex-type connector (see figure 3.9). The is keyed to prevent misconnection.

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Figure 3.9 ATX auxiliary power connector.

The pinouts of the auxiliary connector are shown in Table 3.4.

Table 3.4 ATX Auxiliary strength Connector Pinout

Signal

Color

Pin

Pin

Signal

Color

Gnd

Black

1

4

+3.3V

Orange

Gnd

Black

2

5

+3.3V

Orange

Gnd

Black

3

6

+5V

Red

If your motherboard does not function a adjustment auxiliaryconnector, it probably wasn't designed come consume a big amount the power,and the assistant connector indigenous the power supply can be left unconnected. Ifyour strength supply is rated at 250 watt or larger, you must ensure the it hasthis connector and that your motherboard is qualified of agree it. This easesthe load on the main power connector.

ATX12V Connector

Power for the processor originates from a maker called the voltage regulatormodule (VRM), i beg your pardon is built into most modern motherboards. This maker sensesthe CPU voltage requirements (usually via sense pins ~ above the processor) andcalibrates itself to provide the proper voltage to operation the CPU. The style of aVRM permits it to operation on one of two people 5v or 12v because that input power. Most have used 5vover the years, but many are currently converting come 12v since of the lower currentrequirements at that voltage. In addition, the 5v already might be loaded byother devices, whereas, typically, just drive motors use the 12v. Whether theVRM on your board supplies 5v or 12v depends on the specific motherboard orregulator design. Many contemporary voltage regulator ICs room designed to operation onanything from a 4v come a 36v input, so the is approximately the motherboard designer as tohow they will be configured.

Although many motherboard VRM draft up with the Pentium III andAthlon/Duron usage 5v-based regulators, a transition is underway come use12v-powered regulators. This is since the greater voltage will significantlyreduce the present draw. Together an example, making use of the very same 65W AMD Athlon 1GHz CPU,you finish up v the levels of draw at the assorted voltages displayed in Table3.5.

Table 3.5 level of attract at various Voltages

Watts

Volts

Amps

Amps in ~ 75% Regulator Efficiency

65

1.8

36.1

65

3.3

19.7

26.3

65

5.0

13.0

17.3

65

12.0

5.4

7.2

As you can see, using 12v to power the chip outcomes in only5.4A the draw, or 7.2A presume 75% effectiveness on the part of the regulator.

So, editing the motherboard VRM circuit to usage the +12v power feed wouldseem simple. Unfortunately, the standard ATX 2.03 strength supply style has only asingle +12v lead in the main power connector. The assistant connector has no+12v leader at all, so that is no help. Pulling up to 8A an ext through a single18ga. Wire giving +12v strength to the motherboard is a recipe because that a meltedconnector.

To augment the supply of +12v strength to the motherboard, Intel developed a new ATX12V strength supply specification. This to add a 3rd power connector, dubbed the ATX12V connector, especially to supply extr +12v strength to the board. This connector is presented in figure 3.10.

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Figure 3.10 one ATX12V power connector.

The pinout of the +12v power connector is shown in Table 3.6.

Table 3.6 ATX +12v power Connector Pinout (Wire next View)

Color

Signal

Pin

Pin

Signal

Color

Yellow

+12V

3

1

Gnd

Black

Yellow

+12V

4

2

Gnd

Black

If you are replacing your motherboard with a new one that calls for the ATX12V link for the CPU voltage regulator, and yet your existing strength supply doesn't have that connector, simple solution is available. Merely convert one that the peripheral strength connectors to an ATX12V type. Computer Power and also Cooling has released simply such one adapter that deserve to instantly make any type of standard ATX power supply right into one with an ATX12V connector. The concern is not whether the strength supply can generate the essential 12v—that has always been easily accessible via the peripheral connectors. The ATX12V adapter displayed in figure 3.11 solves the connector problem quite nicely.

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Figure 3.11 ATX12V adapter from computer Power and Cooling.

ATX Optional Connector

The ATX specification also defines one optional six-pin connector. Thisconnector has actually two rows of 3 pins each to carry out the signals and also voltages.The computer can usage these signals to monitor and also control the cooling fan,monitor the +3.3v power to the motherboard, and administer power and grounding toIEEE 1394 (FireWire) devices.

This connector has gone through number of revisions in pinout since first beingpublished, and I have actually yet to see any kind of motherboards or power provides on themarket that actually support it. In fact, the recent ATX/ATX12V power SupplyDesign guide published through Intel states, "Details the the 2x3'Optional strength Connector' stated in the ATX 2.03 Specification areomitted from this architecture guide until such time as the signal on the connectorare more rigidly defined."

Table 3.7 lists the pinout that the optional connector as characterized in the ATX2.03 Specification.

Table 3.7 ATX Optional strength Supply Connections

Color

Signal

Pin

Pin

Signal

Color

White/Black Stripe

1394R

4

1

FanM

White

White/Red Stripe

1394V

5

2

FanC

White/Blue Stripe

Reserved

6

3

+3.3V sense

White/Brown Stripe

The FanM signal enables the operating device to screen thestatus that the strength supply's cooling fan so the it can take appropriateactions, such as shutting under the mechanism if the fan fails.

The motherboard (under operating mechanism control) can use the FanC signal withvariable voltages to manage the procedure of the power supply's fan,shifting it right into a low power state or shutting that off totally when the systemis in sleep or standby mode. The ATX standard states that a voltage of +1v orless indicates that the pan is come shut down, whereas +10.5v or more instructsthe pan to run at full speed. The system designer can define intermediatevoltages to operate variable-speed fans at assorted levels. If the power supplydoes not incorporate a variable-speed fan circuit, any type of voltage level higher than +1von the FanC signal is taken as a command to operation the fan at its complete (andonly) speed.

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The 1394 connectors are for powering an optional IEEE-1394 (FireWire oriLink) bus top top a motherboard. The 1394V pin provides voltages native 8v to 40v torun FireWire peripherals off the bus, and also the 1394R pen is a return or groundline for this power circuit. This separate power rail keeps the 1394 bus powerseparate indigenous the system main power to avoid interference.