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Since some time my PC gives (3 beeps, pause, 3 beeps, reboot) repeatedly on boot. Nothing on the screen. Googling for this beep code gave me no meaningful results (it's certainly not a keyboard problem). After many (around 30) tries of booting, it sometimes gets through and then I can use my PC for days (without powering down) without a problem. But once a few days my screens are black, keyboard lights frozen. After restarting my PC, I'm again faced with the boot issue.

My first though was that it is a GPU problem, as I could boot when I removed my GPU and used my motherboard video. However, that seems to have been a fluke.

Today removing the GPU didn't help as well and I started investigating further. I removed all devices attached to my PC. I unplugged all SATA cables (I don't have an M.2 SSD), removed my GPU, used a different PSU and removed 2 of the 3RAM sticks, changing which one of the 3 I used. I did a CMOS reset and used a new CMOS battery. I still couldn't boot, with the same beep code.

I plugged everything in again and started the boot loop. After about 20 minutes the PC finally booted successfuly. After confirming the UEFI default settings, and a rather long boot, Windows started without problems.

So... that's the current situation. I can use my PC but I'm afraid of rebooting it or powering down for any reason.

I guess it must be something related to the motherboard or CPU as I ruled out virtually everything else.

I can just buy a new motherboard and CPU (and probably RAM, because this one is still DDR3), but it would be nice to know what happened.

Any ideas?

My hardware:

Summary
    Operating System
        Windows 10 Home 64-bit
    CPU
        Intel Core i7 4770 @ 3.40GHz    41 °C
        Haswell 22nm Technology
    RAM
        24.0GB Dual-Channel DDR3 @ 790MHz (10-10-10-30)
    Motherboard
        ASRock H87M Pro4 (CPUSocket)    34 °C
    Graphics
        IPS235 (1920x1080@60Hz)
        D2343 (1920x1080@60Hz)
        DELL P2412H (1920x1080@60Hz)
        2047MB NVIDIA GeForce GTX 660 (ASUStek Computer Inc)    34 °C
    Storage
        232GB Samsung SSD 840 EVO 250GB (SATA (SSD))    31 °C
        931GB Seagate ST1000DM003-1ER162 (SATA )    29 °C
        931GB Samsung SSD 850 EVO 1TB (SATA (SSD))  30 °C
    Optical Drives
        No optical disk drives detected
    Audio
        NVIDIA Virtual Audio Device (Wave Extensible) (WDM)
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  • Is this computer custom built or was it built by an OEM?
    – MMM
    Dec 2, 2020 at 13:46
  • Get a manual for your motherboard and look up the beep code. Beep/error codes are different for every motherboard manufacturer because they are specific to a BIOS.
    – LPChip
    Dec 2, 2020 at 13:53
  • Are you sure the beep is a long beep instead of a short beep? 3 short beeps followed by a pause and another series of 3 short beeps is a memory problem. If you had a faulty memory module, but it had not completely failed, what you describe makes sense. I had memory fail in a machine that had not been turned on for a week. So it’s happens; A new motherboard would be new memory and processor you would basically be building the entire system again since your using a legacy Intel socket
    – Ramhound
    Dec 2, 2020 at 13:56
  • Given the symptoms you have, my suspicions are a problem with the motherboard itself. Possibly some traces that are conducting badly. By having the machine turned on for a long time, the temperature inside your case rises, which causes metal to expand which fixes the traces. May be a capacitor problem too. I would start looking into replacing the motherboard given all the tests you've done.
    – LPChip
    Dec 2, 2020 at 14:19
  • This is a custom built PC. It's 3 short beeps, pause, 3 short beeps. The PC is always on (camera monitoring and other stuff). Letting it cooldown before booting may explain the behavior. I'll check the memory again just to be sure I don't buy a new motherboard and cpu for nothing. @Ramhound, where do you find this description of this beep code?
    – Coder14
    Dec 2, 2020 at 14:23

1 Answer 1

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From the text dispersed here and there, I'd guess the culprit is on the motherboard, seems to work as the MoBo warms up a bit... so a broken PCB-trace, possibly. One might need quite advanced tools to find (=locate) the actual problem.

One step further, and a possible problem removal step:

  • It isn't just the RAM modules: The RAM needs to have working communication via the databus and memory access/control lines (RW, CS, and all that), from RAM to CPU and vice versa.
  • Use a pencil eraser - lightly - to erase the oxide (air oxygen induced "contamination") on the RAM module contacts.
  • Get some "contact spray" from an electronics supplier (note: nothing else than that!) and spray it on the CPU-socket and RAM module connectors (on MoBo and modules)

... you might solve the problem by those two steps.

I have removed strange effects on old computers by very similar methods. Old oxidized connectors will not allow current to flow as freely as required for correct function.

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  • Thanks, that sounds plausible. I might try that out later, but in the meantime I ordered a new motherboard, CPU and RAM. I need to be able to depend on my PC so I can't be sitting with fingers crossed hoping it will boot soon.
    – Coder14
    Dec 2, 2020 at 20:23

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