Powers down when 8pin CPU power plug is applied

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Candan

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Jul 27, 2014
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Hi guys.

New build.

6700k
Asus Max VIII mobo
Seasonic SS 750 gold.

When I power up. System tries to spin up for half a second then shuts off. I've been able to determine that it's the 8pin cpu power EATX12V CPU plug that is causing it, since it doesn't happen when it's not plugged in. Why would this be?

Nothing else is connected at this point, other than the 24 pin mobo plug. I was adding power plugs one by one to see where the issue was coming from after the complete build.

Please help!
 
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I was looking closely at picture and it raised a question in my mind....did you have to install the metal standoffs for the heat sink. (I'm don't have an intel "I" series build ever so I don't know)

the reason I ask is those stand offs are covering several traces on the motherboard that go to the cpu did one scrap the traces leading to a short? ive never seen standoffs cover traces like that usually the traces go at least 1/8" away from stuff like that.

this is a question to you and any intel experts out there but that just doesn't look right to me. from any of my computer builds, usually have a space between that stuff.
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Candan

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Jul 27, 2014
237
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Ok. Here's what I've tried to no avail

- Different PS.
- Breadboarded mobo out of the case to see if it was shorting.
- Removed DIMMs
- Remounted CPU.
- Nothing plugged in to mobo apartment from 24pin and 8 pin power.

Same issue. Fan spins for a second then stops. Motherboard remains illuminated.

Brand new mobo and brand new CPU.

Thoughts? Thanks
 
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maxwellmelon

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Oct 2, 2013
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remove the cpu and heatsink and turn the power on. does the power supply stay on?

FYI congrats on breadboarding your down to determining if its a cpu short, bad motherboard or psu.

if it stay powered on with cpu out - cpu is shorting out somehow/somewhere
if it powers down theres a short in the motherboard as theres nothing left to test.

in case you wonder the power will turn on even with no cpu. it just wont do anything of course
 
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maxwellmelon

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also I'm not an intel expert but ive seen other post where the cpu heat sink being to tight can cause issues so mabe if it runs without the cpu try reinstalling the cpu and just lightly tighten down the cpu heatsink.
 
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maxwellmelon

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Oct 2, 2013
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I was looking closely at picture and it raised a question in my mind....did you have to install the metal standoffs for the heat sink. (I'm don't have an intel "I" series build ever so I don't know)

the reason I ask is those stand offs are covering several traces on the motherboard that go to the cpu did one scrap the traces leading to a short? ive never seen standoffs cover traces like that usually the traces go at least 1/8" away from stuff like that.

this is a question to you and any intel experts out there but that just doesn't look right to me. from any of my computer builds, usually have a space between that stuff.
 
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Candan

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Jul 27, 2014
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You could be right. Although the back plate is well raised and insulated, the standoffs on the top might be an issue. When I removed them to have a look, I noticed that the little black gasket that sits around the base of the screw (have a look at the pic on the link) was missing from the screw that was in the hole where the standoff fits. Looks like some exposed copper there now. Could have been shorted by the screw... doesn't look as if the stamped circuit tracks are damaged though.

So, tomorrow I'll try to power up without those stand offs. I don't want to mount the cpu and fan again just to see if it POSTs. Think it would be ok just to check running it breadboard without the fan for just a few seconds?

https://www.dropbox.com/s/6738uw3mu6otnku/20160625_212937.jpg?dl=0

 
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maxwellmelon

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I unselected so you can select the right one if others look though the post in the future.

Yes that def a short. I wonder if that is common on intel motherboards are like that or not because to me that seems like just bad design. I hope the rest of you build goes fine now. have fun.

also you should just be able to sit the heat sink on top of the cpu gentley to do a quick test without the brackets installed. I still wouldn't turn it on ever without a heat sink even sitting on top of the cpu.
 
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Candan

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Jul 27, 2014
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Thanks. Instead, I am going to return the mobo to my local computer store! I know they will look at the cpu pins, and they're fine. I only bought it a few days ago, and can do a 14 day exchange!
 
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