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Thread: PC restarting issue

  1. #1

    PC restarting issue

    Hi all, I'm after some advice about my pc that has developed a weird fault, turning itself on and off randomly.

    When left plugged in:
    It turns itself on randomly (often in the night), part powers up then restarts. This can happen multiple times before finding the pc on and running.

    When switched on from the socket:
    This often (75%) of the time starts the pc (no pressing of on button req'd)
    The pc starts, runs for a few seconds - often enough for the counter on the mobo to show the normal "on" number - then stops and restarts, sometimes several times before it runs normally.

    When pressing the start button (on mobo or front of case)
    Pressing the case start button ends with the same result, 75% of the time it starts, runs for a few seconds then restarts, often several times. 25% of the time it turns on as normal.

    Recently it's just cycling through the start on its own-runs for a bit-turns off endlessly, seemingly ignoring the button presses on the mobo and / or the case.

    When it does start and run it remains running fine for often hours.

    In all cases, the power supply fan doesn't spin - I don't know if its detecting this then stopping or if the fan only spins when it is hot.

    Things I've tried with no apparent change to the situation:
    I've disconnected the power switch & reset button.
    The ram has been reseated.
    The gfx has been reseated
    All usb devices have been removed
    Ethernet has been removed

    I think it's something to do with either the mobo or the power supply and would be really grateful if anyone else has experience with a similar issue to give me an idea about which needs to be changed or where to start looking.

    Thanks in advance for any advice

    Build:
    Case: CORSAIR CARBIDE SERIES™ AIR 540 GAMING CASE
    Processor (CPU): Intel® Core™i7 Quad Core Processor i7-4770k (3.5GHz) 8MB Cache
    Motherboard: ASUS® MAXIMUS VI HERO: PCI-e 3.0, SATA 3.0, USB3.0
    Memory (RAM): 8GB KINGSTON HYPER-X BEAST DUAL-DDR3 2400MHz X.M.P (2 x 4GB KIT)
    Graphics Card: 2GB NVIDIA GEFORCE GTX 760 - 2 DVI, HDMI, DP - 3D Vision Ready
    1stHard Disk: 120GB KINGSTON HYPERX 3K SSD, SATA 6 Gb/s (upto 555MB/sR | 510MB/sW)
    2ndHard Disk: 1TB SEAGATE ST1000DX001 1TB/8GB SSHD 64MB HYBRID DRIVE
    Power Supply: CORSAIR 750W RM SERIES™ MODULAR 80 PLUS® GOLD, ULTRA QUIET
    Power Cable: 1 x 1 Metre UK Power Cable (Kettle Lead)
    Processor Cooling: Super Quiet 22dBA Triple Copper Heatpipe Intel CPU Cooler
    Sound Card: ONBOARD 6 CHANNEL (5.1) HIGH DEF AUDIO (AS STANDARD)
    Wireless/Wired Networking: 10/100/1000 GIGABIT LAN PORT - AS STANDARD ON ALL PCs
    USB Options: MIN. 2 x USB 3.0 & 4 x USB 2.0 PORTS @ BACK PANEL + MIN. 2 FRONT PORTS
    Operating System: Genuine Windows 8.1 64 Bit - updated to win10

  2. #2
    That can be tricky to in down, but I'd start with the power supply. Re-seat all the connectors, especially taking note that the motherboard power connector is level and fully seated with the clip locked in.

    Next, I'd take all the ram out and try booting with just one ram chip installed. If that seems to calm things down, test each ram chip one at a time to see if you have one bad one.

    Check all power cables to any drives.

    If all cables from the ps have been re-seated and you've tested all the chips - check your bios settings and make sure Wake on lan is disabled. You may have something on your network that is sending a packet to the NIC that is waking up the system.

    Check all your sleep settings.

    If that all doesn't help - it may be time to replace the mobo.

    Taking everything apart and carefully re-assembling, adding in one components at a time is the only way to isolate the issue.

    HTH
    Not complaining, just an observation.

  3. #3
    Check the ATX plug, it will have a (likely thinner) green wire (the PS_ON# pin shown here: https://en.wikipedia.org/wiki/ATX#Power_supply); make especially sure that's not pushed part-way out of the plug housing or otherwise bad. It's an unlikely culprit given the failure mode, but would be the cheapest to fix.
    Dem white knights nerfed muh mershn!

  4. #4
    Thanks for the suggestions GJ51 & Shadowdancer.

    I'll give it a good going over later today and make sure everything is seated correctly and the ram sticks are ok.

  5. #5
    Great advice already just to add my 2 cents..
    The Good news is there is a 3 year warranty on the PS if it is dying(no fan sets alarm bells ringing to me). I have just fixed a system with the same power supply also with an asus MB, check you have surge protection on in the advanced bios settings.

    Do the symptoms change with the side panel removed, I noticed the rather rigid shrink rap on the PCIe power to the video card caused the connector to be under pressure and distorted slightly
    If at first you don't succeed, skydiving is not for you

  6. #6
    Regarding the PSU. The fan kicks in when the PSU reaches a certain temperature. Normal behavior with my Corsair RM650i.

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    i5 6600K @4.7GHz on air / 16G DDR4 2400 / Asus Z170 pro gaming / 1080Ti / Rift CV1 / X52pro Hotas

  7. #7
    Sounds like a PSU problem. Get that replaced asap. If you are in the UK Novatech do their own high quality PSU's that don't cost the Earth.

    Oh and come on you have i7-4770k @3.5 Ghz, when it should be at 4.5Ghz. Any chip with a K on the end has free Mhz and in your case a whole Ghz

  8. #8
    I doubt it's a PSU issue. Sounds more like a circuit problem on the system board. A PSU doesn't turn a PC on by itself. The mobo is the one controlling whether to supply the said power from the PSU to the other components to bring them into the "on" state.

    The part about turning itself on is weird, and highly suspect.
    http://raptr.com/badge/FoxTwo/fs_9c1bc5a32225832b7b8053a08ce2bbf0.png

  9. #9
    You can do a very basic check on the PSU by shorting that PS_ON pin (green wire) to any ground (black wires). As long as those are connected, the supply should stay on. Since your fan doesn't move while the supply is cold, testing it can be a bit of a hassle unless you have something that you can plug in, e.g., a case fan with one of the big 4-pin connectors.

    If you have a multimeter at hand, you can check if you have a voltage between ~2.6–6V on the PWR_OK line too, if that is absent or unstable, the supply is failing internal tests. After powering the supply, you should of course also see the proper voltages on the supply lines. Be careful though not to short the +12V or +5V lines since they can produce a lot of current which isn't dangerous but can lead to sparks and spontaneous welding at short range
    Dem white knights nerfed muh mershn!

  10. #10
    Originally Posted by Necronaught View Post (Source)
    Oh and come on you have i7-4770k @3.5 Ghz, when it should be at 4.5Ghz. Any chip with a K on the end has free Mhz and in your case a whole Ghz
    4770K is notorius for sub-optimal thermal solution under the lid, getting a stable OC is hit and miss with the chip, riddled with temperature problems.

    Friendliest Meteor Police that side of Riedquat ... and keep it under Lightspeed!
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  11. #11
    Originally Posted by FoxTwo View Post (Source)
    I doubt it's a PSU issue. Sounds more like a circuit problem on the system board. A PSU doesn't turn a PC on by itself. The mobo is the one controlling whether to supply the said power from the PSU to the other components to bring them into the "on" state.

    The part about turning itself on is weird, and highly suspect.
    I just finished a new server build tonight. Fired it up, installed the drives and the OS. Had everything running nicely. Shut it down to install a quad port NIC. Guess what? Putting the NIC into the PCIe slot booted the computer up.

    After that - I made sure to unplug the PS before add/remove any hardware. First time I've had that happen.

    Wake on Lan settings as well as USB components, kybd, mice are just a few of the things that can fire up a PC.
    You can search and find the commands to input into a command line in Windoze to report what was the last cause of a startup.
    Not complaining, just an observation.

  12. #12
    Originally Posted by GJ51 View Post (Source)
    I just finished a new server build tonight. Fired it up, installed the drives and the OS. Had everything running nicely. Shut it down to install a quad port NIC. Guess what? Putting the NIC into the PCIe slot booted the computer up.

    After that - I made sure to unplug the PS before add/remove any hardware. First time I've had that happen.

    Wake on Lan settings as well as USB components, kybd, mice are just a few of the things that can fire up a PC.
    You can search and find the commands to input into a command line in Windoze to report what was the last cause of a startup.
    In the first post, OP has mentioned he REMOVED all those. Plus, I would have thought it's common knowledge by now not to plug/unplug anything into PCI/PCIe slots without pulling the power plug and waiting about 10 to 20 seconds? Everything has a "sleep" mode now... OFF doesn't mean OFF. Damn "intelligent" machines!

    It's actually the very first thing I do whenever I open up a server to do some fixing. Power plugs out (all of them), waiting a minute or so, before I would even add/remove anything.

    Originally Posted by xzanfr View Post (Source)
    Things I've tried with no apparent change to the situation:
    I've disconnected the power switch & reset button.
    The ram has been reseated.
    The gfx has been reseated
    All usb devices have been removed
    Ethernet has been removed
    So, PC turning itself on is very strange.
    http://raptr.com/badge/FoxTwo/fs_9c1bc5a32225832b7b8053a08ce2bbf0.png

  13. #13
    Thanks once again for all of the helpful suggestions and advice on this issue, here's an update for those interested:

    I've reset the cmos using the jumpers, checked the cmos battery with a meter and stated taking out everything one by one (usb devices, ethernet - there’s no wireless, gfx, hd's, checked both sticks of ram independently) until i was down to just the mb which I removed and checked for cracks or issues obvious to the naked eye, and it still cycled through the on & off. I then reversed the procedure adding items with the same results. Power supply on its own just sat there with no signs that it was trying to start itself so I've narrowed it down to either the mb or the main cable from the mb to the power supply.

    The cable between mb and power supply doesn't appear to be damaged (e.g. a break or short going to the "power up" signal wire) so I think that it’s the motherboard. This would fit with the logic that the mb is sending the "power up" signal to the power supply when it shouldn’t, with no influence from anything plugged in to it. There is a noticeable "click" when the power cycling starts which sounds like the relay in the power supply is being triggered in the correct manner, and not some short internally.

    It was left for 1/2 hour and it went through several on/off cycles before ending up staying on for an hour or so then going back to a couple of cycles then staying on. If it stays on for long enough, powering off from windows then restarting from the case power button looks to be a way of getting it to bypass the cycling however this is highly likely to be luck / superstition as it doesn't always work!

    As its not an easily repeatable issue I think that the problem is either a couple of things coming together (which I've hopefully ruled out) or linked to environmental factors e.g. a tiny crack or dry joint that is affected by heat or moisture and only requires a very minor change to open up or close. I will give it one last check on the cable with a meter & look at the surge protection element in the bios but I'm not hopeful.

    TL;DR: I think it’s the motherboard.

    Bad news is that the money saved for a new GFX is going to be spent on a mb or mb/processor combo
    Good news is i get to go component shopping

    As a quick aside, this is the first pc that I've specified online and bought ready constructed rather than building myself so I put up a similar post on the suppliers official forum. I haven’t had a single reply on that thread but dozens of helpful, knowledgeable ones on this so thank you all, you're ace!

  14. #14
    Originally Posted by xzanfr View Post (Source)
    TL;DR: I think it’s the motherboard.
    There's an easy way to eliminate/confirm whether it's PSU or system board. If you have a spare PSU (or borrow from a friend who does), just hook the spare one up. If it still does the same thing, well you have your answer.

    But yeah my initial thoughts were that it's the system board, not the PSU. I always have a spare PSU lying around, for these kinds of troubleshooting.
    http://raptr.com/badge/FoxTwo/fs_9c1bc5a32225832b7b8053a08ce2bbf0.png

  15. #15
    I recall a build from a few years back that would magically turn itself on at the strangest of times.

    Disabling Intel Rapid Start technology fixed that - but this was 5 or 6 years ago, and I'm not sure that is even on modern boards any more.
    Drunks of Sol, Drunks of Sol, drunken spaceships full of lol

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