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Warning This article is design to educate the PC enthusiast any changes to wiring or products can and will void warranties.. These are strictly guidelines anyone that uses them is doing so at your own risk... 


PC Wiring Stuff 12v DC


Basic Wiring Pin Outs

Tricks & Tips


Things to keep in mind before any project.

  • Never touch or play with wire while the PSU is plugged in!!!!!!!!!!!!!!!!!!!!

  • Keep in mind you always want to be very careful when using power and never assume anything is correct double check and re check.. 

  • Its a good Idea to draw out your ideas before any work is done.

  • If you are a novice or first timer bounce the your ideas off someone else that has experience in wiring. 

  • Most important is Planning,  90% of your time should be spent on the planning part the actual work is very little.

  • Do it right the first time and work safe..

  • Remember you are dealing with electricity and it must be respected bad things can happen if you are not careful..


Basic Wiring Pin Out Diagrams for ATX Style PC's


     Lets start this article with a list of the most common connectors you will find in a PC.. Then we can expand and discuses just how to make cables and convert voltages and uses. Most of the wring we will be dealing with are basic PC AC/DC power from an ATX style power supply.. 



Illustration 1.1: 4-Pin 12v Power / 24-Pin ATX Power


Illustration 1.2: 20-Pin ATX Power



Auxiliary Power Wiring


     Most ATX power supplies come with one of two power connections for you motherboard. Either a 20-pin or a 24-pin versions they do make converters if you happen to have the wrong type for your motherboard...


Illustration 1.3a: Standard 4-Pin 12v Molex Connection



Illustration 1.3b: Standard 4-Pin 12v / Floppy / Serial ATA / Aux Power / Molex Connection


     There are two different standard 4-pin Molex connectors a 12v used for drives and CD/DVD-ROM's and the 5v Floppy type connectors. Some power supplies the newer versions come with two addition power connection types for newer products like SATA and PCI-e ports blow are examples of these....



Illustration 1.4: Standard 3-Pin 12v Motherboard (Fan Jack)



USB & Fire Wire Diagram


     You may also run into 3-pin variable 12v Fan connections used on your motherboard. Note that some fans will come with two or three wires the third wire is a sensor wire used to evaluate performance and in some situation regulate the voltage running to the fan...

Illustration 1.5: Default IEEE 1394 standard Pin out Fire Wire


Illustration 1.6: Default USB Pin out Motherboard


     Two other common wire connections for your motherboard are the USB and Fire Wire pin outs. These are used very frequently for additional ports commonly provided with the newer cases for front terminals.. As you can see from the images above the USB and Fire wire have very similar board mounts but the wiring is very different. It is important to always read carefully the documentation and make sure you use the proper connectors in the proper place.. Just because the look the same doesn't mean they are..



Warning This article is design to educate the PC enthusiast any changes to wiring or products can and will void warranties.. These are strictly guidelines anyone that uses them is doing so at your own risk... 


Tricks and Tips for conversion cables and Wiring How To's



Bypassing a power supply connector to turn on a PSU.



     What you need to do from the 20-pin motherboard Mole connector take a wire or a dual mail Molex piece and bridge or short out the PC_ON and the Ground wires. Use the diagram and photos above for examples.. An alternative for those not comfortable with wiring is to buy a jumper made specifically for this task they are very inexpensive but considering what they are they should be.. has them and example is HERE. This is useful for checking out drivers or devices without contaminating a system or requiring the us of an existing PC.. We use this all the time to test fan's and lights..




Illustration 2.1: 24-Pin ATX Jumper Diagram

Illustration 2.2: 20-Pin ATX Jumper Diagram






Conversation for 12v 4-Pin Molex Terminals 


     This section will show you the basics needed for most wiring setup on a PC. most combinations using standard Molex connectors. This is very useful when hooking up a series of fans and you need to make wires for specific voltages.



Illustration 2.3: Image on Left is the pin out for a 7volt setup the right is for 12volt Both are for Peripheral or stock 12v 4-pin Molex connectors.......






Molex Floppy Terminal Pin Out

Pin Name Color Description
1 +5V   Red +5 VDC
2 GND   Black +5 V Ground
3 GND   Black +12 V Ground (Same as +5 V Ground)
4 +12V   Yellow +12 VDC




Fan Wiring and the Fan Bus



Don't Let this happen to you!!!!!!!!!


     One of my personal pet peeves when it comes to PC's is the fan connectors I can't stand wires everywhere. It not only looks bad but allot of the time it prohibits airflow increasing internal case temp and causing your PC to run inefficiently.. That is why I always suggest getting rid of them pesky extra fan connectors whenever possible. 






     One way of hiding and consolidating your wire problems is with a fan bus. A fan bus also provides multiple extra ports for the serious Over Clocker or gamer to add some extra air flow. The idea behind a fan bus is simple.. Take a bunch of wire ends make a series of connectors and run a current threw them. How fancy you get is up to you add in switches diaphragms for speed controls LED to power indicators.. Anything you feel fits your PC and style. Just about every review site has their version so I will just link a few of my favorites. Hopefully they give you the idea..




4-Pin to 3-Pin Fan Conversion

     Another way to deal with the overload of 4-pin Molex Fan connectors is to convert from the 4-Pin to the 3-Pin motherboard terminals if you motherboard has extras that is.. Depending on the fan it is pretty strait forward.


     Start with the fan clip and strip the wires leading to the Molex terminal.. Purchase some 3-pin terminals along with the ends. Using the diagram bellow make sure you hook up the pin properly. Most fans using 4-Pin Molex connectors do not have a sensor lead so you will only need the two pins connected to run the fan..







Power2Go, The easy way to burn your favorite media


Warning This article is design to educate the PC enthusiast any changes to wiring or products can and will void warranties.. These are strictly guidelines anyone that uses them is doing so at your own risk... 




Marns CDA




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