Extremely weird POST problem, all troubleshooting tested

[Fire Yoshi]

So I've got the weirdest of problems.

Short story:
I bought parts for a new computer a week ago, put them together, and boom it worked on the first power-on. Hurray!
Parts:
Intel Core i5-4690K
Gigabyte Z97MX-Gaming 5 motherboard
8 GB Avexir Core Series DDR3-1600 RAM


I could access the BIOS (Gigabyte F4 BIOS), everything worked normally, etc. etc. etc.
So I went to sleep.

The next morning, I try to power on my computer. It goes:
Zzzz- ... Zzzzzzzzzzzzzzz- ... Zzzzzzzzzzz (POST)
3-4 restarts before it POSTed.
Well, that's weird.

Next thing you know, it wouldn't POST at all. Ever. It's still like that as of today.
I tried every single troubleshooting option in the sticky of this forum, contacted Gigabyte support, Intel support, NCIX support... everyone told me something different. And nothing has fixed it.

Here's the thing that happens now:
System powers on for 2 to 3 seconds then shuts down.
Powers on again for about 5 seconds then shuts down.
Powers on again for a full 30 seconds.
THERE IS VIDEO OUTPUT (A FLASHING WHITE UNDERSCORE ON THE SCREEN)
It lasts half a second, system shuts down.
Powers on again, does exact same thing indefinitely.

Help? As I said, I've tested pretty much everything, every component, my only two remaining possible culprits are the motherboard and the CPU. Intel guy told me it's the CPU, Gigabyte guy told me it's the motherboard, NCIX guy told me to try to troubleshoot everything again.

The winner will get RMAed.

Edit:
With a speaker plugged into the motherboard, I do not ever get any kind of beep whatsoever, even in classic "trouble" situations like no RAM installed for example.

[ELSknutson]

its the motherboard

I have this problem all the time

(i work for HP)

[iLenovo]

Fix: It's usually the motherboard, I suggest you get compressed air and blow air all over the motherboard (connectors etc..)

[Fire Yoshi]

Fix: It's usually the motherboard, I suggest you get compressed air and blow air all over the motherboard (connectors etc..)

Sadly, it's brand new, and every connector is in mint condition, so I highly doubt it has to do with dust or grime 

 

its the motherboard

I have this problem all the time

(i work for HP)

Are HP mobos that bad? 

[iLenovo]

Ye

Sadly, it's brand new, and every connector is in mint condition, so I highly doubt it has to do with dust or grime 

 

Are HP mobos that bad? 

To be honest I feel bad that your PC has something to do with HP. Yes they are really that bad as you asked.

[dragoon20005]

Sadly, it's brand new, and every connector is in mint condition, so I highly doubt it has to do with dust or grime 

 

Are HP mobos that bad? 

take it apart and test each parts one by one\

 

place the mobo on the box and also physically check if the board has any damage

 

test with one stick of RAM

 

and also use only the onboard display output.

[Fire Yoshi]

take it apart and test each parts one by one\

 

place the mobo on the box and also physically check if the board has any damage

 

test with one stick of RAM

 

and also use only the onboard display output.

Already tried all that. No apparent damage to the board either. And I've tried with both onboard display (GPU removed) and GPU output, does the exact same.

[dragoon20005]

Already tried all that. No apparent damage to the board either. And I've tried with both onboard display (GPU removed) and GPU output, does the exact same.

oh

 

well i guess your mobo is a dead one

[Fire Yoshi]

oh

 

well i guess your mobo is a dead one

That's what I'm thinking

[ELSknutson]

Sadly, it's brand new, and every connector is in mint condition, so I highly doubt it has to do with dust or grime 

 

Are HP mobos that bad? 

lol yes

also there power supplys

[Litargirio]

-snip-

 

I've had the same problem recently; computer would turn on for a bit and immediately back off. Turned out to be a faulty PSU. Did you try jump-starting yours to see if it works by itself?

 

http://seasonicusa.com/RMABeta/JumpStart/JS.pdf

[Fire Yoshi]

I've had the same problem recently; computer would turn on for a bit and immediately back off. Turned out to be a faulty PSU. Did you try jump-starting yours to see if it works by itself?

 

http://seasonicusa.com/RMABeta/JumpStart/JS.pdf

Tried, PSU works fine.