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  1. #1
    May 2017

    Computer doesn't always start when powered on

    Hello, I'm new around here, I hope I'm in the good forum,

    It's been a while since I got problems with my computer.
    A couple months ago, from time to time, the PC would not start up when I hit the power button. The motherboard's LEDs were lit, however nothing happened. Usually, I just turned off the PSU until the LEDs fade out, then turned on the PSU again, and then the PC would boot up.

    Now the problem is slowly getting worse. I have to wait at least an hour minimum when it happened, sometimes an entire night. It is pretty random, however once it's started everything works just fine, gaming and stuff. It restarts OK too but if I shut it down 90% of the time it will not come up. If I don't leave the PSU off (and the power coord disconnected) for the night it certainly won't power on the next day.

    When the computer is in sleep mode, it acts the same as being shutdown. When I wake it up by any being, my case's LED (that is flashing when in sleep), after a couple seconds, fades out to not come up again (when it flashes, there's no fading effect or anything)

    I disassembled my PC to further investigate. I tried without the GPU (specs bellow) and with only one stick of RAM, but it looks like it doesn't help.

    CPU: Intel Core i7-3770 (Non K)
    RAM: 2x 2x4GB sticks of some kind of Corsair Vengeance high-profile RAM (1600Mhz)
    Motherboard: ASUS P8Z77-V DELUXE (probably the issue here)
    GPU: EVGA GeForce GTX 960 SSC
    PSU: EVGA SuperNova 850 GS (btw it works when using a jumper)

    I will try to reset the BIOS to defaults.
    Do you have any idea of what could be the cause of this problem? The oldest components are almost 5 years old (that includes the motherboard), so maybe it's only about to die naturally...
    Thanks in advance

  2. #2
    Jun 2012

    Re: Computer doesn't always start when powered on

    Being eVGA, I believe the PSU is relatively new but right now it's my first suspect. Have you tried swapping out the PSU with a known good one? Yes, I know you can jump it, but best way to confirm it's not the PSU is to remove it from the equation and see if the problem persists. Also, past experience has told me PSUs are the most likely component to fail.

    Second would be the mobo - I would look at the capacitors and see if any are bulging or leaking (the website's in Chinese but the pictures are good).

    Hope this helps.

  3. #3
    May 2017

    Re: Computer doesn't always start when powered on

    Hello, thanks for the reply

    I checked the motherboard for any suspicious capacitors. They all look correct, none of them are leaking, neither do they have a weird shape.

    As of the PSU, I don't have one on hand right now. I originally though it was the issue at first; by the way, when I used the jumper on it to check if it worked, the fan would turn on when the switch was ON, but when I turned it off then back on, the fan wouldn't spin (with ECO off). I had to wait, again, a little while. Same behavior as with a motherboard on it.
    I'll try to get one so I can check it.

    Thanks for the guidelines

  4. #4
    Oct 2001

    Re: Computer doesn't always start when powered on

    Sounds like you got it narrowed down. Power supply is probably your culprit. And as Btdog suggested checking caps, you can do the same for the power supply by removing the shell or looking through the air vents to see if there are leaking caps in it or hot spots near power transistors.

    Click here to visit Onetech's website
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  5. #5
    May 2017

    Re: Computer doesn't always start when powered on

    I took a risk and got myself another PSU, and actually all those problems seems to be gone! The PC starts on demand and now I should be able to put it in sleep knowing it will wake up.

    Unfortunately, it's making both fan and electrical noise which are both annoying but maybe in a few days they should be fixed.
    Thanks for helping me out! I'm happy that the motherboard is not the problem, otherwise it would have been almost impossible to replace it with another.

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