# How do I wire a 4pin molex to 3pin for 12V??? Molex 4 pin M/F to 3 pin female



## LegendaryGamer (May 27, 2007)

I've been looking around the internet for answers to wiring my own Molex 4 pin M/F to 3 pin female for my Thermal-Star 7 thermometer??? The Thermometer / Fan Bus can power 4 fans with 4 temperature sensors. The unit itself powers up to 5V but can power 12v fans. The connection is a molex male/female but I only have a 3pin male port to plug it into so my question is how can I wire the molex to powr the unit and the fans??? 

The unit has 4 wires. The yellow wire is 12V and there are two black wires for the ground and a red wire for 5V. I need to wire it for a 3pin if possible. What are my options?? I have all the tools to do the wiring except a tester other than testing from the game system. Im modding my Xbox 360. I have a 3 pin front soldered and working which I found from http://forums.xbox-scene.com/index.php?showtopic=549063 .

I can wire it to the motherboard but trying to avoid more soldering on the motherboard. I've seen cables onling but the shipping is a rip off for a $2 cable they want $6-$8 shipping! I have extra molex 4 pin male/female cables and some male/female 3 pin. Is there a giude on how I can do this?? I did the search engine already with no luck. Thanks for any help.

LegendaryGamer


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## WarEagleAU (May 27, 2007)

Usually, you can get a 3p to 4p connector. They make them for fans and molex connectors on psus. Have you tried that?


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## LegendaryGamer (May 27, 2007)

WarEagleAU said:


> Usually, you can get a 3p to 4p connector. They make them for fans and molex connectors on psus. Have you tried that?




What is psus??? With what I mention can I just make my own cable?? I have some extra molex 4 pin m/f cables and some extra 3 pin m/f Y connectors.


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## Frogger (May 27, 2007)

looking at the mod.. the 3pin from the MB is only 12v  and the input on the -star 7 needs both 5v&12v ,see pic...    you need to rethink your mod...


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## LegendaryGamer (May 27, 2007)

Frogger said:


> looking at the mod.. the 3pin from the MB is only 12v  and the input on the -star 7 needs both 5v&12v ,see pic...    you need to rethink your mod...



I noticed that and that's why Im asking about my options?? Now the Motherboard has 5v,7v, and 12v sources but Im trying to avoid soldering on the motherboard again. If it is possible to make a 12v  connection with the yellow wire and a ground wire and a 5v connection with the red wire and a ground wire. There are four wires that go into the device. The device coonection for a PC is a 4 pin molex
m/f.

LegendaryGamer


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## Frogger (May 27, 2007)

according to the x-box mod your 3 pin is only 12v... where?? are you going to get the 5v without soldering the MB again


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## LegendaryGamer (May 27, 2007)

Frogger said:


> according to the x-box mod your 3 pin is only 12v... where?? are you going to get the 5v without soldering the MB again




Sorry my from a misunderstanding. I have a xbox 360 and here are the power sources on motherboard http://www.xboxchopshop.com/catalog/man_360_volts.php and this http://forums.xbox-scene.com/index.php?showtopic=505106 . So I have the sources and length in the wires once I cut the molex ends off but I wanted to have this done through a connection. Though you have a point which im trying to get the answers for also which is how can I power both at the same time other than soldering to motherboard. If I have no other choices then that is what I'll do. Thank you for helping also.

LegendaryGamer


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## Frogger (May 27, 2007)

Why don't you just insert  the needed wires from the 4 pin in to the right conectors form the main ,pic and go right to your star-7


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## Namslas90 (May 27, 2007)

Probably the wrong kind of connector but;


http://www.youtube.com/watch?v=HKKKRADtimA


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## LegendaryGamer (May 27, 2007)

Frogger said:


> Why don't you just insert  the needed wires from the 4 pin in to the right conectors form the main ,pic and go right to your star-7



Thanks about that though I heard it is bad to draw power from the DVD power supply. I can use the power from the usb port because on controllers are powered from it. The back usb port is powers a laptop cooler that cools the bottom of my xbox 360. 

Im trying to keep the device on the right side of the game system where it is more space there. Can run the wires through the case. So your saying it would be best to just solder the wires to the motherboard for power than making a connection cable???


LegendaryGamer


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## Frogger (May 27, 2007)

if you are not comfortable soldering on the MB then you should make a cable and draw the power from the plug  ...if you have no problems with the solder job then that's the way to go ...


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## Namslas90 (May 27, 2007)

all molex fan voltage conversions here;(3v to 5v,5v to 7v etc);

http://www.ocforums.com/showthread.php?t=372297&highlight=volt+mod.


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## LegendaryGamer (May 27, 2007)

Namslas90 said:


> all molex fan voltage conversions here;(3v to 5v,5v to 7v etc);
> 
> http://www.ocforums.com/showthread.php?t=372297&highlight=volt+mod.



Thank you I seen that site and tried to register for answers but waiting on amistrator to reply. I've been seening how I can provide both sources in one connection. The connection that came with the device is a 4 pin molex so I assume 4 pins can power both fuction since that what was provided?? I was tring to see can I get that through a 3 pin?? Though I will have to just solder where wires to the board I see.

Anyway this site seems better anyway because of the quick responses. I do mean quick!  Thank you guy and gals for all the help you are giving! 


LegendaryGamer


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