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New Computer Randomly Turns On? Help!

Last response: in Systems
December 18, 2012 4:57:55 PM

So I finally caved over black friday and decided to build a new computer. Everything with the build (frame rates, benchmarks, overclocking, etc.) seems great so far except for one thing. The computer will randomly turn on from a full shutdown. It is not happening at a specific time, and it can happen anywhere from 5 minutes to 5 hours after shutting down the computer. I have also used the computer for long enough that I can safely say there are no stability issues, and it has never randomly turned off after days of use. It only turns on. Here is the build as is:

CPU: i5 3570k
Motherboard: Asus P8Z77-V Pro
Memory: G.SKILL Sniper 16 Gb
Cooler: Corsair Hydro H100
Video: EVGA GTX 670 FTW 2 Gb
SSD: OCZ Vertex 4 256 Gb
HDD: Seagate 3 Tb
Optical: Asus BD Burner
PSU: SeaSonic X Series X650 Gold
Case: NZXT Phantom 410
OS: Windows 7 Professional

I have tried the following with no success:
- All "Wake On" features in the advanced power management of the BIOS are disabled.
- Disabled automatic installs of windows updates.
- Disabled wake timers in the sleep settings.
- Disabled Wake on LAN for the Intel network controller in the device manager.
- Since I don't have issues with it turning off, I even thought it may be a flaky power switch making a brief connection here and there, so I disconnected the power switch header from the motherboard after shutting down. This didn't work either.

Are there more software options? Is it even possible for a hardware problem to cause these kind of symptoms? I've built many computers over the years, but I am at a complete loss as to what the problem is now and would greatly appreciate some help!

More about : computer randomly turns

December 18, 2012 6:53:04 PM

It sounds like the motherboard is turning itself on.

You may try taking it out of the chassis completely. Put it up on a table all together but outside of the case, and keep an eye on it.

All a switch or button is, is a controlled short between two sources. Perhaps there is some grounding issue with the chassis+mobo that's causing the board to think it's received a power on contact.

If that doesn't work, then I'd ship it on back and get a different board.
December 18, 2012 9:12:28 PM

Yeah, I'm afraid it's a hardware problem at this point. If it's the motherboard on the case though, wouldn't you expect it to always be shorted since it's screwed in place? That would make me think it should boot straight away after a shutdown, and possibly randomly turn off after having contact for more than 5 seconds.

Do you think there is a possibility that something could be up with the power supply? If there is too much ripple on one of the lines, could that cause the system to begin booting? I'd rather exhaust other options, if there are any, before swapping motherboards. That's such a pain.
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December 18, 2012 9:22:17 PM

It would have to be shorting the two pins on the power supply that are shorted when the switch is engaged. You can turn on power supply's with a paper clip, but I've never seen a power supply randomly fire up. Otherwise it'd be pretty documented issue with the millions of power supplies out there.

It looks like the last step before swapping out the motherboard, would be to remove it from the chassis to rule the chassis out.
December 19, 2012 4:24:19 PM

Thanks for the info, I'll give that a try today. No point in further putting off the inevitable, I suppose.