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PC won't post / Ran through NO BOOT steps to no avail

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June 23, 2012 7:21:38 PM

After attempting to install a new video card, my PC will no longer boot. It's an i5, maybe 2-3 years old, self-built.

The machine first started fine, but a wire was hitting a fan making a loud noise, so I shut it down. After moving things around to prevent the wire issue, I tried turning the machine on, but it would not even post.

I have reshuffled components, removed all unnecessary components and cards, and still it will not post.

The current behavior:

When I hit the power switch -- and with a single case fan plugged in, along with the 4-pin CPU and 20-pin ATX MB plugs -- it appears that the case fan starts for a split second, then stops.

I have run through all the steps on the no-boot/post thread, including:

- limiting power connections to only CPU and motherboard
- breadboxing outside the case (still would not post)
- removing all cards and components (RAM, etc.)
- resetting CMOS
- testing the PSU (an Enermax 460w) -- first with paperclip test, then installed in another PC where it worked
- tested an alternate PSU (420w) in the non-working PC -- does not even appear to start at all, even for a split second
- checked capacitors -- none appear to be bulging from what I can tell
- reseated CPU and heatsink fan
- cleaned the case and components with compressed air (was dusty before, but at least it worked!)
- no speaker sounds


I've tried everything I can think of, and everything from every thread I could find on this type of behavior -- I think I must have somehow fried or shorted the motherboard during this process. This PC had worked perfectly until my attempt to install the video card -- but again, even without that new card in, it won't post.

Interestingly enough, if I plug in just the 20-pin ATX plug (and leave the 4-pin CPU plug disconnected), the PSU appears to start up for maybe a full second (fans spinning, including the CPU heatsink fan, etc.)< and then powers down. This repeats non-stop until I flip the PSU switch. But maybe that is expected behavior and doesn't help isolate anything...?

Or could this indicate that it's the CPU itself? Could I need to reapply thermal paste between the HS & CPU -- maybe it's overheating instantly, or there is a connectivity issue to the HS?

It's only 2 or so years old, so I can't imagine this suddenly being an issue -- that's why I am leaning toward the motherboard being fried. But I'm trying to isolate the root cause before I start spending money on replacement parts.

But hopefully someone can tell me it is indeed the MB, and then I can stop banging my head against the table trying to troubleshoot this.

Any and all help is greatly appreciated. Thank you kindly!

JF
a b B Homebuilt system
June 23, 2012 7:44:20 PM

check the wires..sounds like you have a cut wire and it shorting out the mb. or the wire shorted out and zapped the mb.
with just the cpu and power supply does the fans spin at all?? can you see any melted wires or chips. i would check inside the pci slots and ram slots for bent pins.
June 23, 2012 8:32:46 PM

^ +1.

You may have also damaged the board with static if you started rearranging wires without grounding yourself (though its unlikely)
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June 23, 2012 8:42:48 PM

smorizio said:
check the wires..sounds like you have a cut wire and it shorting out the mb. or the wire shorted out and zapped the mb.
with just the cpu and power supply does the fans spin at all?? can you see any melted wires or chips. i would check inside the pci slots and ram slots for bent pins.



I don't see any bent pins. No wires that appear split.

Now wondering if maybe when I went to arrange wires if some sweat dripped on to the MB -- it was hot as hell when I attempted this...
June 24, 2012 1:27:22 PM

Gallarian said:
^ +1.

You may have also damaged the board with static if you started rearranging wires without grounding yourself (though its unlikely)



I did find this - looks like something might have burned here? Link to photo:

http://t.co/Paog46Ge

I'm about to pull the trigger on ordering a new motherboard, but am gunshy in fear of frying another.

Best solution

June 24, 2012 3:05:50 PM
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Ah.. yeah that doesn't look great :\ Think you may have found the issue there mate.


Dont be afraid of trying again, you just got unlucky!
June 24, 2012 3:08:34 PM

Thanks for everyone's input -- glad I can chalk this one up to foolishness and bad luck, and at least point to the motherboard as the root cause. Off to order a new one!
June 30, 2012 5:43:34 PM

Best answer selected by joshfox.
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