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Breadboarded - Fried MOBO

Last response: in Motherboards
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December 6, 2011 1:29:25 AM

Hello.

I think I fried my mobo, but I figured I'd ask you all whether I should try a new mobo first or a new PSU.

I built my first computer and after a few minor issues, everything worked other than the case fans. When I say everything worked, I mean all components were in the case working, I had successfully installed windows, and I had begun installing additional software.

Looking online, I finally figured out that I needed to plug in my fan controller to the PSU, an OCZ ModXstream-Pro 600w. In my excitement to fit the last piece into the puzzle, I connected the stock fan controller in my NZXT Phantom case by the molex connector without first turning off the computer. Immediately, the computer turned off. Now, when I press the on button, the cpu and psu fans briefly spin up (less than a second) then turn back off.

I've removed the PSU and run the "paper clip" test. It runs fine, and I even connected the fan controller to it. Now my case fans work, just the rest of my computer doesn't.

I've stripped the mobo and taken out of the box, placing onto a cardboard box. I've removed everything but the cpu and cpu fan. When I connect the PSU, the cpu fan starts to spin then shuts of immediately. Same with the PSU fan. No lights on the mobo light up. The Dr. Debug on my ASRock z68 Extreme3 Gen3 does nothing. There are no beeps.

Do you guys think I should buy a new mobo first or a new PSU? Since the PSU can run alone and run the case fans, does this mean it is not damaged? Are there any other steps I can take? Should I try to power the mobo without the CPU?
a b V Motherboard
December 6, 2011 1:32:48 AM

edited by nna2
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a b V Motherboard
December 6, 2011 1:46:39 AM

Before doing anything else try clearing the CMOS. It could be that your setup is messed up and it doesn't know how to start up.

The fact that the fans work is not a clear indication that the PSU is working. The PSU has multiple voltages output to the various parts of the mobo, +12v, -12v, +5v, -5v, +3v . You only need to have one output not working for it to cause the whole computer to fail. The fans get power from +12V only. Could you take it to a local computer store and have them check it for you? Or, if you know how, get a voltmeter and make sure that all of the voltages are present and at the correct voltage.

I suspect that the MOBO is dead but it wouldn't hurt to check out the PSU as well.
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December 6, 2011 2:00:37 AM

Thank you both for the quick replies. I pulled the CMOS battery out and tried it. Nothing. Put it back in. Nothing.

I read somewhere on these forums how to check the voltages. Just plug a voltmeter into different combinations of wires in the 20+4 connector right? I guess it would be worth it to try that before buying a new mobo that I maybe don't need.
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a b V Motherboard
December 6, 2011 2:04:33 AM

If you can you could also hook the PSU up to another computer just to be sure it works.
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Best solution

a c 156 V Motherboard
December 6, 2011 2:07:56 AM

JK, it is safer to use a good power supply to test the questionable motherboard.

I'd check the PSU first.

Running fans only indicates that the PSU can provide some minimal amount of 12 volt power.

Try to substitute a known good power supply. If you cannot, use a DMM to measure the voltages. Measure between the colored wires and either chassis ground or the black wires. Yellow wires should be 12 volts. Red wires: +5 volts, orange wires: +3.3 volts, blue wire : -12 volts, violet wire (standby power supply): 5 volts always on. The green wire should also have 5 volts on it. It should go to 0 volts when you press the case power button, then back to 5 volts when you release the case power switch. Tolerances are +/- 5% except for the -12 volts which is +/- 10%.

The gray wire is really important. It should go from 0 to +5 volts when you turn the PSU on with the case switch. CPU needs this signal to boot.
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December 6, 2011 2:18:51 AM

I am a photo enthusiast more than a computer enthusiast. This is my first build and I don't have access to any other computers besides laptops and macs, so I can't test the PSU on another computer. Testing the voltages should be just as good, though, right?
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a b V Motherboard
December 6, 2011 2:20:06 AM

Yes, it will be fine.
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December 6, 2011 2:22:36 AM

Thank you all so much. This is such a helpful forum. I'll pick up a DMM tomorrow morning and order the appropriate part when I get the results. Cheers.
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December 16, 2011 3:20:18 AM

Best answer selected by tduggan2.
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