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Motherboard wiring

Last response: in Motherboards
August 22, 2011 4:58:25 AM

So I just replaced my Alienware Area 51 PSU (750W) with a Corsair 850W so I can do SLI. I had never rewired anything like this and it was a bit involved. All went fine except the 24 pin cable that alienware used between the motherboard and the PSU plug had a small 3 pin cable (with thin black and red cables) that ran to the edge of the case and plugged in. I had no idea what that plug did but since I had to rewire everything I had to unplug it.

Anyone have any idea what type of small 3 pin plug might be coming off my motherboard 24 pin plug on an Alienware system? Can I live without it?

I had to replace all the wiring because Alienware used a 64 pin plug on their PSU so every system component ran into one large plug that then went into the PSU. To replace the PSU I had to replace all the cables.

Thanks for any suggestions. I just don't want to suddenly find I turned off something major like a fan. I can't check the side fan because to see it I have to remove the side which would turn it off.

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a b V Motherboard
August 22, 2011 6:26:14 AM

OK, I have no idea lol. But could you clarify a couple of things?

This was what model Alienware system? Have you tried to download its manual and see what that 3-pin thingee is?

If I understand you correctly, Alienware ran a 24-pin to 24-pin cable where one end plugged into the mobo, and the other end plugged into a 64-pin psu socket. On the psu end of that cable, there was a 3-pin connector. Was there anything similar on the mobo end?

If not, was the wiring between the 2 24-pin plugs straight thru? IOW, do the pins on the mobo plug electrically correspond to the pins on the psu plug? And the three wires that terminated in that 3-pin connector connect to which pins on the 24-pin plug?

(The thought here is we might be able to identify what the connector does by looking at the standard pin-out of a 24-pin mobo plug.)

3-pin might indicate fan or maybe a detector to signal the case has been opened.
August 22, 2011 2:41:32 PM

hi...This is an Alienware, Area 51 system (about 3 years old). Unfortunately the manual for my system doesn't go into great detail about the inside of the case. This particular system had a PSU that had a 64 pin spot for a plug. All the components of the system all were wired into one large 64 pin plug that went into this PSU. This is why in order to add a new PSU, I had to rewire the entire system. There was a 24 pin connector to the motherboard that ran into this plug that went to the PSU. I replaced that 24 pin cable but when I was removing Alienwares cable I realized that off the 24 pin connector (on the Motherboard end) there was a thin red and black wire connector that ended in a tiny 3 pin plug that plugged into something at the edge of the case. The 24 pin connector that came with my PSU did NOT have this small attached cable as part of their 24 pin connector. I just had to unplug it and forget about it.

I'm just not sure what that plug was for. I've called Alienware but now all their customer service is out of India and honestly..they don't know how to help someone who's system is more than 6 months old. I was just hoping maybe someone would know what cable might run from the 24pin connector to a spot in my case.
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August 23, 2011 6:08:25 AM

I actually solved this. I opened the other side of my case and with a flash light looked through my cabling to see that the side fan was indeed not working now. I guess that small cable brought power to the side of the case. I just pulled the cable free and ran it across to the motherboard plug. Not ideal if I have to take the side off but at least the fan is working now.
a b V Motherboard
August 23, 2011 6:15:52 AM

Glad you solved it without having to look at which of the 24-pins those wires were connected to.