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I think my PC is possessed; it only turns on when it wants to.

...Jokes aside, my PC is not turning on and the symptoms are very strange and, to some extent, apparently random. I need help identifying the problem and suggestions on how to fix it.

Here are the specs:
PSU: Corsair AX1200i
Motherboard: Asus Rampage IV Extreme
Processor: Intel i7 3630k
Cooler: Corsair Hydro H100
RAM: 2x Corsair Vengeance 4GB 1600mhz (8GB)
Video: NVidia GTX Titan Z (Asus-produced, original NVidia model specifications)
SSD & HDD: 3 drives - 1x 128GB SSD + 2x 1TB HDDs (in RAID-0)

These are the symptoms:

  • PC worked fine for a little over a year.

  • Motherboard's lights seem normal (it has power).

  • PC (usually) doesn't respond to the power buttoms (neither front-panel nor on-board), at least not to power-up, but sometimes will turn on during an attempt (after something like 3 days of trying). Conditions for turning on are apparently random.

  • Turning off for a few minutes (5-15ish...maybe 30ish) doesn't trigger the problem; It can be turned on as normal after brief turn-offs, sleeping (can sleep the whole night, will turn on next day), restarts and resets. Problem only happens after long turn-offs (longer than an hour or a couple of hours).

  • I have already checked the external and internal cables and connections to the best of my knowledge (Warning: My knowledge is basic; it extends to what the manuals told me should be correct + basic electrical knowledge akin to "if the metals aren't touching anything, they probably aren't short-circuiting". I'm not an expert and you should only put moderate trust in my judgement. If you strongly suspect something related to connections or circuitry, say so!)

Extra:

  • My no-break will beep (enter battery-mode?) sometimes in the morning, even with the PC turned off, and I've already verified it's not a power-outage. I have tried different outlets and without the no-break, to no success. But it's not out-of the question that, although it was remade recently and should be ok, it may be the case that my house's circuitry may not be giving appropriate power for the "peak" of power-on of the PC (It is a beast PC, and my outlets are 127v except for the shower...I don't know if it's possible, but I'm starting to suspect that, and would like confirmation if possible).

I thank you for any help or effort of help in advance. TheLima.


New developments: After turning my PC off during the last thunderstorm to hit my city (Porto Alegre), my PC failed to turn on, as expected. However, after 3 days of attempts with no result, it suddenly started turning on by itself for a couple of seconds, and then turning off again.

I am still unsure about the cause of the problem, and , facing the lack of an alternative PSU to test the system with, along with the new symptom, I decided to do the "paperclip test". I know it doesn't confirm that the PSU is working properly as a whole, as it lacks testing of other connectors, but at least it can test the mechanism for starting the PSU up, which is now an integral part of the symptoms.

Sure enough, the PSU runs; so to my limited understanding, I think the problem is with the MB, and it is most likely in the process of becoming, well, dead.

I'll get myself either a PSU tester, or a multimeter, to confirm if the other PSU connectors are working, since it's good to have one anyways. But considering that, to my limited understanding, at least the PSU would turn on, even if briefly, if the MB's start-up circuit was ok, which it doesn't, then the MB is likely to be the faulty component.

One extra detail: The PC starts to turn on by itself after some time with power running through the PSU. When the switch at the back of the PSU is flipped off, and then on, it takes some time (30-60ish minutes) for the behavior to start happening again; so it is likely to be an accumulation of electricity in a faulty circuit near or at the startup parts of the MB...I don't think I'll be able to recover without replacing the MB (if the full test of the PSU turns out ok), but I'll try checking all the wiring and MB-placement on the case for contacts again, and I'll keep you informed about the results.

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    Can you test with a different PSU?
    – Karan
    May 19, 2015 at 21:50
  • Not at this time. I don't have any spares. But I will try to borrow a suitable PSU from a friend. PS: The OP was written from a laptop, but I'm talking from my PC right now. It decided to let me turn it on again, just about exactly an hour ago. May 19, 2015 at 23:20

2 Answers 2

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It's almost certainly a flaky power supply. I've experienced the exact behaviour you're describing, as well as a host of other very weird symptoms, with flaky power supplies. They're cheap enough that I usually keep at least one spare around. You might be able to find a repair shop that will let you try one of their spares. You don't have to physically install it in the case to test it.

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  • I am unsure of what you mean by power supply. Are you talking about the Corsair AX1200i? Or my no-break (which I recently discovered is a "short-break" rather than a proper no-break, and that this difference can cause major issues)? --- Either way, I don't have any spares, nor easy-access, for either...so it'll have to wait a bit for me to test... Jun 5, 2015 at 0:25
  • Yes, the thing that supplies power to the computer, which you previously identified as PSU: Corsair AX1200i.
    – boot13
    Jun 5, 2015 at 2:21
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This can be a flaky power supply but also, given that some times the power buttons aren't responding as they should I'd probably consider cleaning up the pc components as static electricity is a real pain in electronics (and it can come from any source).

Also, is your PC plugged into a grounded outlet so that any spike/static is discharged by the ground cicuit?


Edit: Some explanation to get the static out based on comments:

You should have one of these then no?

http://www.worldstandards.eu/electricity/plugs-and-sockets/n/

If you have a Type N outlet, you can simply run a wire from the 3rd socket hole/screw (if your home isn't grounded, there should be no wire there) and connect it to something like a drain pipe or some metal object so that the electricity is dispersed through there.

To "clean" the devices of static electricity, whwat most people say, is to do a Power cycle. Or, in normal peoples' terms:

1) disconnect the tower from everything electric (all the cables, from the backside of the tower)

2) Press and hold the power button for 10-30 seconds, and release. To be sure, press it and let go at the end of that time.

3) Dress some sneakers and touch the computer case (on the metal side) and at the same time, some metal object, you should feel a slight "shock" upon touching, that would mean that the electric charge has been dissipated through you.

What that will do, is force any electricity that is inside the Condensers to be discharged by "forcing a power on" (to prevent damage when touching the case) and then, the touching part is to get the static outside the computer. For the wire grounding part: follow this : http://www.wikihow.com/Ground-an-Outlet

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  • About the power supply, I have the same doubt about your answer as I just commented to boo13's. --- About electrical grounding, the short answer is no; and the long answer is that my house doesn't even have grounding; only neutral; which an electrical engineer told me aren't the same thing, and that neutrals can actually introduce electrostatic rather than dispersing it. Which is why the PC outlet is not neuted either. Jun 5, 2015 at 0:27
  • Yes, ita the psu (psu stands for Power Supply Unit) its the corsair one listed first on your specs. Regarding the grounding, you can do it yourself with no danger and be specific to that outlet only. What country do you live? (so I can know the type of outlet you may have)
    – wadge
    Jun 5, 2015 at 7:43
  • Brazil, and it's an apartment on the 4th floor. --- Also, how would I proceed to clean the components from static electricity? Jun 8, 2015 at 12:08
  • edited answer to better explain the issue
    – wadge
    Jun 8, 2015 at 14:01
  • New developments; Appended to the end of the OP. Jun 10, 2015 at 19:34

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