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[Solved] Desktop wont boot fully.

Last response: in Motherboards
August 14, 2012 2:26:03 AM

Hello, this is my first time posting on these boards but from what I've seen there are a lot of very experienced people here so I'm posting a problem I am having while trying to fix a family members computer. It seems he bought a lot of parts to build his first computer, they arrived in the mail a few days ago and he put it all together but it seems that he mistakenly plugged the PCI-E 6 pin connector into the 8 pin 12v ATX MoBo connector. I have a little more experience than he does so he brought it to me and I have been troubleshooting it all day but still cant get it to boot. One of the cables on the PCI-E cable was fried literally burnt up so I had to use another to plug in the GPU but other than that I don't see any physical damage to the machine.

So basically my question is can anyone tell me exactly what he destroyed by plugging in 6 pin connector in the 12 ATX port?

Any help would be seriously appreciated and if at all possible it would be nice to salvage the MoBo but if not that's fine too.

Best solution

a b V Motherboard
August 14, 2012 3:10:37 AM

Does it seem to boot but no video? Does it not power on at all? Little more detail about what it actually does and what equipment we're talking about. Does it show that the board is actually getting any power. Have you tried the simple psu test by jumping the green and a black connector to see if the power supply runs for any length of time. Don't forget to connect at least a fan to it to draw some power from it. Do you have a different power supply to try in case it burnt a psu rail or two? First thing I would try is changing the psu. But is it's a single rail with 25 or 30 amps on it or multiple rails? There's a good chance he burnt more than the psu. But still, it's usually cheaper to replace the psu for trial than anything else. Sorry if I covered things you already tried but I'm not sure what you did try and I know you really can't list everything in one post.

Trying to answer your question about what exactly might have been destroyed by plugging it in the wrong connector is impossible unless you take it to someone who specializes in printed circuit board repair. But I can tell you that the second motherboard power connector usually runs power between the pci-e lane and the cpu's northbridge, usually. So, it could be any number of things. but I would start with the psu. Let us know what you find and we'll go from there.
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a c 331 V Motherboard
August 14, 2012 3:50:42 AM

Both the PCIe power cable and the CPU's ATX cable contain +12v and ground wires. But from the discription of the burnt cable, it sounds like he may have 'forced' it in to the socket using the wrong polarity shorting the +12v to ground. That may have blown the fuse in the PSU or even damaged the board.
August 14, 2012 5:47:22 AM

Sorry about the short ambiguous post. So what happens when I turn it on is the entire machine seems to turn on(The fan on the GPU, PSU fan and lights, case fans and lights) but, there is no image on the monitor, it simply says no input and goes to sleep mode. I tested the monitor to make sure its ports are working by plugging it into my laptops HDMI port and VGA port, unfortunately I do not have spare parts to test a lot of things at the moment but I will be taking the rig to a friends house, who also uses a desktop mainly, to perhaps swap parts to see what has failed. I tried to remove the nonessential hardware piece by piece to see if any of it was causing the problem(Wearing an anti-static wrist band of course) but still no luck.

I have not tried testing the power supply besides plugging it into the fans yet.

This is a list of some of the parts that are in the machine:





a b V Motherboard
August 14, 2012 3:21:49 PM

First thing to double check all connectors - Make sure you have the 8 pin power connector plugged into the board, also make sure you have the 6 pin power connector plugged into the video card.

If the computer stays on but you're only not getting the video feed then the problem is usually either the pcie slot (motherboard), the psu, or the video card itself, (including all wiring going to these parts). I find it hard to believe it will be the video card though because it is designed for that power. Unless having it come up through the pcie slot did it.

The first thing I would check when you get to your friends house would be the psu. Switch yours out with his to see if it resolves the problem. (If you put your psu in his machine it might burn something out.) If it fixes it you know what to get a new one of. If it only does the same thing switch back out the psu's so whatever problem your having doesn't short out his psu.

Next I would try changing out the video card. I would put your card in his machine to be sure it works. If it doesn't come on then you now know what to buy a new one of. If it does come on and works then the next step.

If not that leaves the pcie slot. I would hesitate to put his card in your machine at this point because I would be afraid of damaging it. It should be ok but I'm not going to tell you to do it and have it ruin his card. Again, it should be ok, after all, your card is working on his machine so it didn't hurt yours but. . . I'm not going to tell you to risk his card. If he has an old one laying around and don't mind loosing it heck yeah, give it a try. The other option at this point would be if he has a X4 video card laying around he wouldn't mind loosing if something goes wrong. First try it in the X16 lane and if that don't work try it in the X4 lane. Click for bios in case it boots because you might have to change pcie boot order. Two things, if the X4 card works in the X16 slot you will need to try a X16 card next. It might have only shorted/blown a part of the lane. Secondly, sooner or later you will need to stick an X16 card in that slot. Try yours again or get one on ebay real cheap.

Let's start with that and let us know what you find out. There is a link under my signature that leads you to troubleshooting boot but no video problems. It wouldn't hurt to go through that list and check your equipment 1 part at a time before going through all the hassles and steps from above.
August 15, 2012 11:39:22 PM

Just wanted to comment to close this issue, I took the machine out to a friends place and tested the power source first and it turned out he shorted the PSU with his mistake. Swapping it out solved all the problems and the machine runs fine now.
a c 331 V Motherboard
August 16, 2012 12:10:31 AM I said.
a b V Motherboard
August 16, 2012 1:20:34 AM

And I - First and Repeatedly

Glad you found it and that it was an easy fix.
August 23, 2012 8:00:10 PM

Best answer selected by ebrell.