Question about HP Compaq Motherboard

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Power Supply Connections

I replaced the fan inside the Power Supply and am trying to determine
the placement, if any, for the connector labelled "P9". It has 2 wires,
one black and one white. I may have inadvertantly disconnected while
working on the unit.

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Not every wire that comes off the power supply is used so this might be worrying over nothing. I'd give a quick look at all your components inside- especially the cd or dvd players as well as the CPU fan. If it looks like everything is okay, power it up. When your system runs its POST (power on self test), it'll tell you if something critical is missing. If not, use it as normal. If something really is unplugged, later on you'll find out because it either won't work or a function of it won't work.

Posted on Jan 11, 2009

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My motherboard G31M3-F V2 doesn't power on nothing powers on enven the fans but the power supply seems fine what could be the problem

Best thing I can recommend is check your connections. Are all the power supply connectors plugged in? Your P1 connector, your 4-pin (or 6/8-pin) connector for your CPU?

Can you bypass the switch on your case and jump the power button pins on your motherboard to get it to power up?

Grounding could also be an issue.

What about your graphics card? Has it got the power it needs? Try the onboard or booting without it.

Hope this helps!

Mar 11, 2016 | Computers & Internet

1 Answer

Where does P8 P9 connect?

The P8 and P9 power supply cables may not even go to anything.
The power supply cables coming out of the Power Supply, can be labeled, however that particular pre-built computer manufacturer, deems.

General labeling for the power supply cables is;

1) P1 - The 20-pin ATX main power cable, or 24-pin ATX main power cable.

2) P2 and P4 - The 4-pin ATX +12 Volt power cable

3) P3, P5, P6, P7, P8, and P9, can be used for a standard 4-pin Peripheral power cable, ('Molex'), or a small 4-pin Peripheral power cable, (Floppy Drives/Card Reader), or a SATA power cable.

Here, let me show you a basic example, looking at Power Supply cable connector markings, for the Dell Optiplex 745 Desktop PC,

Scroll down look under the subheading - DC Power Connectors

This link shows you the various power cables, and their respective connectors,

If the problem is a Tyan Trinity 400 S1854 motherboard, let's look at the power cables you need to connect;

To the right of the blue bold - Trinity 400 (S1854) - heading, click on the Manuals icon.

Scroll down to the chart that has - Socket 370 (Intel Celeron / Pentium III ), at the top. In the list click on the blue -

Trinity 400
[ Shows as Trinity 400 (Addendum)
You have the option to click on Trinity 400, or Addendum.
Do not click on Addendum at this time ]

This is a PDF file. The computer you are using now has Adobe Reader on it, which uses PDF files.

After you click on the file name (Trinity 400) it may take up to 30 seconds, before the first page comes up.
Using a medium speed DSL connection, it took 12 seconds just now.

(Wanted you to know, because you will be staring at a blank white page, until the first page comes up. Didn't want you to think the link doesn't work. The file is downloading in the background. The first page is the LAST to come up )

When you are staring at the cover sheet -

Tyan S1854 / Trinity 400 / Motherboard User's Manual / Revision 2.02 -

,bring your mouse cursor to the bottom/middle. The ghosted out navigation guide will now appear.
Go to the far right, and left-click on the Adobe PDF icon.
When you hover your mouse cursor over it -
Show Adobe Reader toolbar - comes up.

Easier to navigate around.
At the top, (Header), is the PDF file page number box. It is to the right of the Down Arrow.
To the right of it, is the Zoom In icon ( + ), and the Zoom Out icon.
( - )
Clicking on Zoom In increases the view size.
Clicking on Zoom Out decreases the view size.

Go to Page 13.
Bring the view size so you are looking at the entire motherboard illustration.
(For me it is 75 percent. I'm using a 26 inch RCA EN-V HDTV, as my main monitor)

You can use the Down Arrow to go page by page; Or,

1) Left-click once in the PDF file page number box.
Contents in the page number box will be highlighted in blue.
2) Type the page number (In this case -> 13)
3) Press the Enter key.

Page 13 is an illustration, Page 14 is a photo; Top View.

A) ATX main power cable.
It is a 20-pin ATX main power cable,

Looking at the illustration it is shown at the far upper right.
ATX power connector.
It is in-between ram memory Slot 3 (DIMM 3), and the Floppy Drive cable's connector.

That is the only power cable that connects to the motherboard.

B) Your IDE (PATA) harddrive, will use a standard 4-pin Peripheral power cable,

DOES NOT MATTER what P number is on it, as long as it is a standard 4-pin Peripheral power cable, you're fine.

In fact you may have some of these power cables left over. Roll them up out of the way, and tie them with a plastic zip strip.. The inside of your computer needs all the air flow it can get.
(Bread tie = NO. It has a metal wire inside. Do not recommend)

C) Your optical drive/s, (CD/DVD drive/s), are probably IDE (PATA) also.
Each one needs a standard 4-pin Peripheral power cable.
Again, DOES NOT MATTER what the P number is.

[ ]

You may have a computer case fan, (Or more than one), that has an adapter cable, allowing it to use a standard 4-pin Peripheral power cable, OR a small 4-pin Peripheral power cable, for power.

(In the Playtool link, the Peripheral power cable example, is a standard 4-pin Peripheral power cable.
The Floppy Drive cable example is a small 4-pin Peripheral power cable.

They are BOTH Peripheral power cables.
The Small, and Standard, are designations that allow you to immediately know what you are looking at.

Newer computers do not use a Floppy Drive. This power cable is usually used for a Card Reader. Hence the need to have a more standard designation, for these two types of power cables.

The Peripheral power cable has been mislabeled as a Molex power cable.
Molex was the first maker of this type of power cable CONNECTOR. The name stuck. Kind of like calling an adustable open-end wrench, a Crescent wrench )

Those small 4-pin Peripheral power cables, can be used for a myriad of devices. (Floppy Drive/s, Card Reader, power to a case fan, etc)

Again, as long as you find a device, that needs it, it does NOT matter what P number is on that power cable's connector.

A computer case fan is supposed to attach to FAN1.
The Brown three pin connector at the end of ram memory Slot 1.
(DIMM1) Power for the fan.

Same thing for the Brown three pin FAN4 connector on the motherboard, above the AGP expansion slot to the left, and to the right of the Game Port. (Joystick)

Same thing for the Brown three pin FAN3 connector, above the CMOS battery, and to the left of the VIA VT82C596B - Southbridge chip.

Same thing for the Brown three pin connector FAN2.
It isn't shown on the illustration, but is in the photo.
It is to the right of the Brown three pin FAN4 connector.

If all of your devices has a power cable, then P8 and P9 may not be used. Just extras in case you find devices that need them.

For additional questions please post in a Comment.

[Main thing is to have the jumpers on the motherboard, set to the correct setting.
Also, at the last make sure your ram memory module/s ('Stick'), are plugged in tightly. You can accidentally bump them loose, when plugging power cables in ]

Jul 02, 2012 | Tyan Trinity 400 S1854 Motherboard

1 Answer

New motherboard will not power up. Power supply OK, No manuals or CD. Need pinout and label on Motherboard for motherboard to case connections for an ACER ECS EG31m V.1.0

[1 2 3 4 5 6 7]
[8 9 10 11 12 13 14]

[Orange White NU NU NU NU NU]
[Green White Blue White NU NH Green Orange]

NU = Not used/No wire
NH = No hole

1-2 HD
10-11 PWR SW
13-14 LAN

May 24, 2012 | Acer Computers & Internet

1 Answer

I have got a system with an Aopen motherboard which having only a 20 pin connector for smps connectivity. the Atx smps i have is is 24 pinned. i can connect the main line by splitting up the 24pin...

The actual Processor fan connects to the CPU Fan header on the mainboard. It's 4 small pins. It plugs in right near the CPU socket on the mainboard. Check the user manual for exact placement, you may download it from the AOpen website if you don't have one already.

Plug in the 20Pin connector if that is the most Pins that the mainboard will allow. Cable tie the other 4Pins back onto the 20Pin connector.

Then if there is additional 4Pin connector required by the mainboard for CPU power and you don't have that connector on you power supply, you will need to purchase a Molex to 4Pin CPU power connector. When you go to the computer store check with them that all is correctly connected.

Take care!

May 25, 2011 | AOpen MX4GER Motherboard

2 Answers

I push the power button It doesn't boot all the fans come on the light come one and a second later it off, then it tries again, it keep trying to cycle but can get anywhere. I have just assembled this...

Test your PSU or replace it if your power supply units fan is not working your PSU is faulty

One bad lead can cause a computer to continue on a cycle or to shutdown or fail to detect your hard drive

Test all leads that attach to your hard drive including electrical extensions,IDE,SATA

the leads from your ((motherboard to your hard drive)) make sure they have a secure connection and are not faulty or just replace them there probably old and faulty
make sure all leads that are attached to your drives dvd\cd 3 1/2 inch floppy have secure connections and are not faulty even the electic extensions or just replace them they are probably faulty a computer needs its connections to have an end so any faulty leads will end up with a computer error hope this helps

Mar 10, 2011 | Computers & Internet

1 Answer

AA8 DuraMAX won't power up

if you are sure that the ps is ok replace the motherboard

Mar 21, 2009 | Abit AA8-DURAMAX Motherboard

2 Answers

Can not get motherboard to boot up

the things youre describing that are not controlled by the same power connectors. the 1st set that works are powered i think by the main large rectangular power connector. the stuff that's not working require more power connections. the cpu fan has a small wire that connects to a small connector on the motherboard right near the cpu. the optical drive connects to one of the the 4 pin power connectors coming from the power supply, same with the hard drive- same power connector. the front usb light is going to connect to a specific tiny 2 pin connector on the mobo, it will be labeled with tiny white letters-- try to find or download the manual. godo luck!

Jan 31, 2009 | Foxconn 848P7MB-S Motherboard

1 Answer

W2646 crapped out

Some eMachines computers (like many from Dell) use a non-standard pin out for their power supplies, so if you try a standard ATX power supply it may not function.

However, in my experience it IS likely to be the motherboard. Luckly I have been able to replace quite a few of the eMachines mobos with a standard mATX mobo, since you can probably remove the IO plate. You'd certainly want to replace the power supply when doing so.

Jan 25, 2008 | E-Machines EMA IMPERIAL GV (845GV) TG3...

2 Answers

Motherboard fried?

the problem is your power supply, since the power supply have differrent output voltage there is 12volts, 3volts and so on. the 12volts output voltage is not giving enough power. you can determine this by detaching the 20pins from your motherboard coming from the power supply then power-on the power supply then use a jumper wire insulated but scraped both ends (conductor visible) then connect it to the green connector and the grey connector if the fan of the power supply doen't rotate then you 12volts output voltage is busted.

Oct 22, 2007 | EliteGroup 915P-A Motherboard

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