Motherboard and components will not respond on power on

CrimsonEon

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Dec 1, 2013
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10,510
Somewhat of a story to this one:
A few months back I had purchased two sets of components to build two identical rigs. One worked immediately, the other, however, had some issues with powering off and on randomly. Ended up determining the GPU was causing a break and had it replaced (solved here http://www.tomshardware.com/answers/id-1909286/power-issues-build.html).

The builds comprised of:
Mobo: -Asus Z87-A ATX
PSU: -Corsair TX750 (refurbished)
CPU: -Intel i7 4770k
GPU: -Nvidia GTX 760
RAM: -2 Sticks 6GB DDR3 (unsure of brand, I'll check when I have time)

The second build worked for a while, but started to have some problems. First, the Asus Z87's Anti-surge protection would trip, causing a restart at times. I read in some places that the surge protection may be too sensitive and disabled it in the BIOS (in retrospect I should have just replaced the PSU). Later, another issue cropped where the display would shut off, the fans would run at maximum and the build would stop responding, but for some reason audio continued to play. It would work normally after a restart.

Now, the build isn't booting at all. On pressing the power button, the Power LED will turn on, the Hard Drives will start to spin, and the PSU fan will turn on. The motherboard, however, will not POST, or respond in any other fashion. The motherboard does not light up aside from a single Power LED (already on when connected to the PSU), and the CPU and Case fans will not respond, not even a quarter-turn like I've seen the last time this build had power problems.

I've attempted to:
-Power the motherboard without the GPU
-Power with one stick of memory in various configs
-Reseating all power cables
-Clearing CMOS
-Checking the CPU's positioning

Bizarrely, after the first night of troubleshooting, I left the build plugged in overnight. Getting up the next day to test one more time, the build went about halfway through POST, rebooted itself, went halfway through POST again, rebooted again, then managed to make it to the BIOS. After this, I tried one last time to reseat the GPU (still in the case), and it started the same problems up again.

To me, the likely culprits seem down to a defective PSU, Motherboard, or a short somewhere. I've had little time to do any proper testing or talk to a repair shop, and I'm tearing my hair out trying to narrow it down. Can anyone lend some advice?

Thanks!
 
Solution
I agree with your lineup of suspects. There is no obvious answer I don't think. Something flaky with the MOBO or PSU. Since trying another PSU is easiest of the two start there. PSUs can of course go partially bad and it isn't uncommon for the PC to partially boot when they do. To rule out a short re-build PC barebones outside the case, might be worth the trouble to try that actually - no drives, no usb devices, nothing hooked to mobo but essentials to POST, because any electrically malfunctioning component could cause this kind of issue.
I agree with your lineup of suspects. There is no obvious answer I don't think. Something flaky with the MOBO or PSU. Since trying another PSU is easiest of the two start there. PSUs can of course go partially bad and it isn't uncommon for the PC to partially boot when they do. To rule out a short re-build PC barebones outside the case, might be worth the trouble to try that actually - no drives, no usb devices, nothing hooked to mobo but essentials to POST, because any electrically malfunctioning component could cause this kind of issue.
 
Solution

CrimsonEon

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Dec 1, 2013
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10,510


Thanks for the quick responses!

That was going to be my next step, I was hoping I wouldn't have to start cannibalizing the first build, but at this point I'd be willing to do so to find out where the fault is. Hopefully I'll have time within the next day to try.

notherdude, just to make sure I have everything straight, do the essentials involve just the mobo and PSU? Or does this include a stick of RAM and/or the CPU?
 

CrimsonEon

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Dec 1, 2013
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10,510

Awesome, I'll give those tests a shot when I can and get back here ASAP.
 

CrimsonEon

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Dec 1, 2013
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Swapped out the PSU from the first build; The second build responded on first, second, and third tries, booting up fully. I'm going to try it for a bit longer to see if there's any shorting issue or anything else with the mobo, but it's pretty much all points to a defective PSU. It'd explain my earlier problems too.

Going to pick up a new PSU and see how well it works. I'll post back here if there's any problems but for the time being, thanks a ton!

If there's anyone that would recommend a more reliable replacement PSU, that'd be appreciated as well.