What can cause a motherboard to short?

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Tigerbite

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Jun 6, 2012
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I've been working on a new build and I can't get it to boot (no power, no fans, nothing). I can't even get the LEDs on the motherboard to light up.

My first power supply I received was DOA. The second one is tested and working fine. The motherboard still didn't boot. So I replaced the motherboard (thinking maybe it was DOA as well.) The second motherboard still did nothing.

I know, it's possible it could be another DOA (but having 2 in a row seems unlikely, especially since I've never received a single DOA ever!)

So now my question is, maybe there's something that's causing the motherboard to short at my first attempt to power on the machine.


I have brass standoffs.
 
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Are the standoffs installed only where there are screws to mount the motherboard to them? Any possibility of a screw, paperclip, or staple on or under the mobo? Does it work out of the case? What PSU (brand and model, not just wattage) do you have, and what are the rest of your specs?
 
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Are you sure your wall outlet is alive and did you turn on the PSU? Also, there could be a 110/220 toggle switch to set somewhere in the PSU. I would try running the board outside of the box. Unplug everything but the RAM & monitor including the HDD. Is it possible the CPU is installed incorrectly?
 
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CPU: i7 2600k
RAM: Corsair Vengeance DDR3 1600 (http://www.newegg.com/Product/Product.aspx?Item=N82E16820145345)
Motherboard: ASRock Extreme3 Gen3
GPU: Radeon HD 6850
PSU: OCZ ModXstream 600w
HDD: 1 DVD, 2HDD (Not sure, they're from old machines)

I tested the PSU with a paper clip (sticking it in the green/black wires on the 24pin connection.) Also, I tried this build with my old psu which is still working fine.

There were/are no loose screw, paper clips, etc in the case or near the motherboard.


I was told by ASRock to try powering it on out of the case. I'm currently at work and can't attempt that til I get home, but my question is: If something shorted it in the case, wouldn't it be dead and not work out of the case? Or if something shorts it in the case, is the motherboard protected and just powers down before something explodes?

Let me know if you need any more information. Thanks for the help. This is really mind boggling.
 
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Another quick question: Seeing as how I didn't have brass standoffs on the first motherboard, would that only fry my motherboard? Or would it fry everything else in the motherboard as well?
 
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Some times a short prevents a computer from working correctly, remove the short and it works fine. Some times a short does permanent damage, but not always.

Bench test the computer. Take the board out of the case and place it on the plastic anti static bag that it came in, on a good sturdy table. Then assemble the parts on the table with out the case. Start with only the PSU Board, Chip, cpu cooler, ram, keyboard and monitor, and gpu only if there is no onboard video. No hard drives no fans no case connectors. Then use a paperclip to turn on the mobo. It should power on post and say no boot disk, or maybe just a blinking cursor.

If you get this far chances are those parts are fine. Then add the gpu and hard drive dvd drive. If all that works there is an issue with something shorting on the case. Reveiw the motherboard mounting instructions for your case.



 
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fix the problem... In this case the problem may be a stand off in the wrong spot, or the lack of stand offs so the mother board is shorting on the metal case. Remove that bad standoff, or remove the computer from the case you should be removing any possible shorts that were caused during installation.

Some times a cheap case on off button is in the closed or on position. If that is the case the computer wont boot.
 
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Chances are you have a brass stand off in the wrong hole i see it all the time people building systems for the first or second time, make sure that each brass has hole for a screw on the motherboard.

All it takes is one extra brass stand off sitting under the motherboard to short out something.
 
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My case actually has 4 raised bumps and that's where I always screw in 4 screws to the motherboard.

So...did I not fry my first motherboard? But probably did fry the second one with the standoffs? >_<
 
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hard to say... what kind of case do you have? Did the case come with any standoffs? Most full atx boards have 9 mounting points. Not that you need all 9 but they are there.
 
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I looked at your board and case.
Your case has 6 raised built in stand offs. You will need to add 2 screw in standoffs. One in the top right and one in the left most side in the middle just below the fan. The screw in standoffs once installed should be the same height as the raised built in ones.
 
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I actually put 4 in. I put one at the top left, top right, left (bottom/middleish) and one somewhere on the right. I put them where I could because I thought I needed them.

Did I put too many? XD (Currently at work, so I'm not exactly sure which holes I plopped them in.)
 
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If they dont line up with a mounting hole on the board, and are lost under the board they are an issue. The metal stand off is contacting things under the board that should not be contacted maybe causing a short. If the board is a little smaller than standard, and you can clearly see that they are not touching anything then the extras are fine.
 
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In your case use these 8 points and remove all extra standoffs.

Case.jpg
 
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Thanks for the picture. 😀
I'll try the bench test you suggested first, when I get home. If that works then I'll know where my standoffs go and maybe it'll work in the case. 😀

But now I just have to hope it works out of the case =x
 
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Okay, so I just did the "bench test". All I had plugged up was the psu, cpu, heat sink. Got nothing, no power, no beeps, no LEDs. :|

Dead motherboard? Dead cpu? Maybe both? If the motherboard was good and cpu was dead would the LED still come on?
 
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