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I know the answer is probably a resounding YES, but I just wanted to double check. I just purchased a new chassis for my PC and now my 4pin cpu power plug doesn't reach. I'm wondering if the 4 pins are required for operation, or can I get by for the weekend without it until I can go get an extension?

Looks like it is mandatory with my Mobo. I tried to post without it and i just got a blank screen. Looks like I'm getting a new adapter asap.

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please don't add "[closed]" to titles manually; those are added automatically when a question is closed. if you've solved your own problem, you can add your solution as an answer, and mark it accepted after a couple of days. – quack quixote Apr 2 '10 at 5:49
up vote 1 down vote accepted

I believe they were referring to the square (but indexed for proper polarity) 4-pin molex connector from the power supply (marked P4) to the motherboard, not the CPU fan's connector. And you can indeed get short extensions for those (as well as for the 3-pin fan-power+speed-detector plugs).

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While you already found the answer yourself, the explanation is most likely that the BIOS doesn't allow you to boot with incorrect data from the fan.

Depending on which side of the connector you used (usually they have find to only allow it so that the right pin would not get connected), you are missing either of the end-pins. The first there are for power, so if you have one of those off the fan would/should never run, the last one is speed control, and that is the one which would usually not be connected in such a case.

However since it doesn't go to POST really, I suspect you connected it so that one of the power pins wasn't connected. Hence no CPU fan at all, and weird power flow (since you put the full-speed power on the speed-control pin), and hence system refuses to go with it.

You could either try flipping the connector (if the fins allow that and it works at full speed then, I had some which would not turn at all if only using 3 pins), or get an adapter. If you go with the first, ideally use speedfan or a similar application to check how the temperaturs and fanspeeds are to make sure everything works as it should.

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sorry, this answer has nothing to do with my question. The fans are in perfect working order. It was more to do with the CPU power. – Chase Florell Apr 6 '10 at 23:25
Ooops, very sorry about that. When I read "4 pin CPU power", my mind involuntarily went to those power connectors for the CPU fans. Anyways, glad you solved it. – Carighan Maconar Apr 8 '10 at 17:15

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