Did I short circuit my motherboard or PSU?

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Yingerman

Yingerman

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Sep 9, 2013
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I dun f***ed up. I plugged a case fan into my motherboard while the computer was running. The fan was already connect to the PSU, but the computer instantly shut down the moment I touched the fan connector to the MoBo.

I tried turning on my computer moments later, and it powered on for half a second (fans, lights, etc.) then shut down. I tried turning it on twice more and it did the same thing. Then I tried again and nothing turned on even a little.

Now, the only thing that turns on is a tiny green light on my MoBo that only turns on when I flip the main power on from the back.

Do you think I fried my PSU or my motherboard?
 
Solution
Benevolence
File an RMA on the motherboard. I think we have enough information to narrow it down to that single component. That being said, you should also buy a PSU tester, as a failure on the PSU could have damaged your board.
BTW don't ever run your CPU without a heatsink attached, it only takes a second to fry a CPU that way. Just trying to clarify what Carlo posted, and that is just don't plug in the HSF fan, but keep the cooler attached.
By all means try the other PSU, as it can narrow out the possibility of your current PSU being damaged.
For a little background info I had a Gigabyte workstation board fry out last year, and it kept rebooting before POST. It was a corrupted BIOS, and because I didn't want to replace the board, I ran it until...
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Benevolence

Benevolence

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Dec 2, 2013
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Two routes for determining the problem. First is to test the PSU, if you can get a PSU testing device, should only be about $20. This will tell you if your PSU is still operational. That takes care of the PSU side, but in the mean time you can try resetting the CMOS with the jumpers, as a sudden shutdown could have corrupted your cmos settings depending on if you computer was in POST when it crashed. If neither of these works...

It's also possible there is a short in your wiring.
Remove all non-essential items from your computer, and add them back in one by one. So start with the cpu, ram, cpu-fan plugged in and nothing else. If it boots, power off and connect everything else one item at a time to the power supply and boot up, rinse wash repeat until you have isolated the short.

If you can't boot with just the motherboard cpu, ram and HSF connected, it's most likely the motherboard, but at this phase we cannot also rule out the PSU.
 
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Yingerman

Yingerman

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I completely unplugged the case fan to no avail. Same problem. What makes you think it's the motherboard over the PSU?
 
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Yingerman

Yingerman

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After waiting a while, I tried turning it on again and it stayed on. Fans, lights, etc. Bad news is there is no video or anything. At least I know it's not the PSU.
 
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unknownofprob

unknownofprob

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Oct 3, 2013
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although that is slightly good, It sounds unfixable.

I can only advise some information;

-I know you have no display, but are you able to hear login sound if you type password and hit enter?

-If you are using a discrete card, try using onboard graphics outputs on the motherboard

Can you hear any beep on startup? If there ever was.

Now, after all that, If you can hear login sound, then I will still bet it on the motherboard but if you have non of your graphics options work, then you will need to replace your motherboard.

 
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Yingerman

Yingerman

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I called ASUS (motherboard maker) and they ran me through some troubleshooting. They told me that because there wasn't a *beep* on startup, that means the processor wasn't getting power. I don't like the sound of that :/. I'm going to swap it out with another computer's power supply and see if that changes anything.
 
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Yingerman

Yingerman

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So if I do that and the CPU is hot, it will tell me that the CPU is getting power and I haven't narrowed down what's causing the problem. If the CPU is cold, that means that the CPU is getting no power and it must be the motherboard. Does that sound right?
 
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Benevolence

Benevolence

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Dec 2, 2013
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File an RMA on the motherboard. I think we have enough information to narrow it down to that single component. That being said, you should also buy a PSU tester, as a failure on the PSU could have damaged your board.
BTW don't ever run your CPU without a heatsink attached, it only takes a second to fry a CPU that way. Just trying to clarify what Carlo posted, and that is just don't plug in the HSF fan, but keep the cooler attached.
By all means try the other PSU, as it can narrow out the possibility of your current PSU being damaged.
For a little background info I had a Gigabyte workstation board fry out last year, and it kept rebooting before POST. It was a corrupted BIOS, and because I didn't want to replace the board, I ran it until the backup BIOS also became corrupted, at which point I replaced the board. It exhibited practically the same symptoms as your motherboard.
 
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carlo_bigtunes

carlo_bigtunes

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it's ok run without heatsink for a 10-20 second,, i'am a motherboard service at indonesia, i'll do that for troubleshoot motherboard.cpu will not fry for a second,
the only thing make cpu fried is , short motherboard or overvoltage from ic clock generator which give cpu voltage.

what motherboard series you have?
 
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Yingerman

Yingerman

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First off, thanks everyone! You were a big help! I testing everything with a different PSU and had the same result, so I ruled that out. I also did what carlo_bigtunes suggested to test if the CPU was getting power (just long enough to feel a trickle of heat), which it was so that didn't really rule out anything. All the symptoms suggested that the motherboard was the problem, so I'll submit an RMA for that tomorrow.

I called ASUS and they told me to submit the RMA with Newegg. If I tell Newegg I plugged in a fan while the computer was on, do you think I'd still get a refund? Partial refund? Will they except it? I've never dealt with Newegg returns, so advice would be appreciated!
 
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