Wrong Motherboard Power Connector

brampel

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Mar 15, 2013
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When putting my computer back together after tidying up, I didn't check which of the two 4 pin connectors coming from my psu I put into my motherboard, and accidently put the one with 4 rounded squares in instead of the one with 2 squares and 2 rounded squares. My computer didn't boot up and the CPU fan doesn't start. I tested the fan with some wires and a battery and it works fine, and I made sure all the other parts worked except for the motherboard and cpu. Is there any way I can fix my motherboard, and is my CPU dead too?
 

knightdog56

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Mar 29, 2008
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Put the right 4 pin connector in the motherboard and try to boot computer, if it does not poer up you most likely fried the mother board. You mst have used a lot of force to connect it wrong after the tiddy up. All you can do is try to see if it will boot.
 

brampel

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Mar 15, 2013
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10,510

It didnt take any more force than usual because the rounded edges fit right in. I'll try what you said.
 

brampel

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Mar 15, 2013
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The motherboard has 4 pins and the power supply has 4+4. One of the 4 pin cables from the power supply is different from the other one and only one matches the motherboard but they both fit. I put in the wrong one and booted the system.
 

brampel

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Mar 15, 2013
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I tried connecting it again and pressing the power button but the cpu fan wont start and nothing happens except for the fans hooked up to the psu starting.
 
From
http://www.playtool.com/pages/psuconnectors/connectors.html

" Motherboards can come with either a 4 pin 12 volt connector or an 8 pin 12 volt connector. Many power supplies come with a 4+4 pin 12 volt cable which is compatible with both 4 and 8 pin motherboards. A 4+4 power cable has two separate 4 pin pieces. If you plug the two pieces of a 4+4 power cable together then you have a 8 pin power cable which can be plugged into an 8 pin 12 volt connector. If you leave the two pieces separate then you can plug one of the 4 pin pieces into a 4 pin 12 volt connector and leave the other 4 pin piece unplugged.

If you look carefully at the image above then you can see the polarization of the pins which prevents you from plugging the cable in improperly. Some of the pins are square and some of them have rounded off corners. The motherboard connectors have matching square and rounded off corners to prevent the cable from being plugged in the wrong way. But if you look really carefully at the right half of this particular cable and then look at the 8 pin 12 volt cable pictured above you'll notice that they don't match. A regular 8 pin cable has four square pins and four rounded ones but the 4+4 cable shown above has two square pins and 6 rounded ones. The left half of the 4+4 matches the left half of an 8 pin cable but the right half is different. Hmmmm... And this isn't some bizarre cable either. I've seen plenty of 4+4s which look like this one. And then there are other 4+4 cables which look just like an 8 pin cable split in two (which makes sense). Since rounded pins fit into square holes in motherboard connectors, this particular cable will fit just fine into an 8 pin 12 volt motherboard connector. But both halves of this 4+4 will fit into a 4 pin 12 volt motherboard connector. You're supposed to use the left half of the cable shown above when plugging it into a 4 pin motherboard connector but the right half will also fit. As it happens, either half will work fine in a 4 pin motherboard because both halves of the 4+4 just provide 12 volts. The pinouts are the same for both halves so either one will work. I'm not sure why they make cables like this one because you'd figure a 4+4 cable would just be an 8 pin cable which splits in two. And you only need one half of a 4+4 cable to plug into a 4 pin motherboard. The other half is unused. But the kind of 4+4 cable shown above is pretty common so don't let it throw you. "


You did not damage your mb by using the wrong connector . Something else is the problem .Recheck all your connectors