After maintenance, PC enters a power-up cycle repeatedly. Issue arises with LGA 1150 connector not fitting properly.
After maintenance, PC enters a power-up cycle repeatedly. Issue arises with LGA 1150 connector not fitting properly.
Details: CPU features Intel i7 4790 LGA 1150 (Haswell), Motherboard model MSI B85M, dedicated GPU was removed during testing, RAM capacity is 2x8GB DDR3, power supply is Gamemax 550W, operating system is Windows 10 (boots normally upon startup). Issue: After cleaning and replacing thermal paste on CPU and GPU, the machine failed to boot properly (starts but doesn’t enter BIOS). Upon inspection of the motherboard, a pin in the LGA 1150 socket appeared missing or damaged. Testing involved removing GPU and Wi-Fi card, not securing the board in the case, and laying the case flat on the floor. Initial setup allowed power-on with fans spinning but no POST. After several minutes, it eventually booted into BIOS and Windows normally. System shut down, reinserted GPU and Wi-Fi, secured motherboard upright, and resumed operation. After that, the PC entered a constant power cycle loop and has not booted since. Questions: Could a damaged or misaligned CPU socket pin trigger this kind of instability? Why did the system briefly POST when the board was flat but failed again after proper installation? Might pressure, grounding issues, or board flex affect contact? Is this likely due to a faulty motherboard/socket, or could the PSU, GPU, or case wiring cause similar problems? Should I continue testing under these conditions? Are repeated attempts risky for CPU or PSU? Any suggested minimal tests to verify motherboard integrity (separate RAM, no GPU, etc.)? If a pin is truly absent, what are realistic repair options? Additional note: When POSTed, the system remained stable in BIOS and Windows. The problem emerges only after reassembly. Advice would be appreciated. Thank you.
I see two possible explanations for the issue. One is more carefully considered: the pin became stuck inside the CPU socket, creating an unintended connection where none should exist. The other suggests the power supply might be failing, as it could be cycling, especially since the system worked after removing the GPU and was stable.
This situation suggests the pin might be completely absent rather than just misplaced. Given the lack of visible debris and the possibility of accidental removal during cleaning, a replacement board could be the safest choice. Repair seems unlikely without confirming the pin’s absence.
I understand there might be a chance the PSU is contributing to the issue, and I need to highlight an important point I overlooked earlier: this isn't the first instance of this pattern occurring. I recently cleaned my PC several weeks back. Prior to that, everything ran smoothly without any problems. Once the cleaning was done, the same symptoms reappeared. At that stage, the machine started up without the GPU and Wi-Fi card, but no display appeared initially. After a few minutes, it restarted, entered BIOS, and booted into Windows normally. However, when I fully reassembled the system and placed the case upright, the power cycling began again. Initially, I thought the GPU or Wi-Fi card might be faulty, so I removed both, but the problem continued. I then left the PC idle for a while. Two days later, I tried it once more, following nearly identical steps (the only change was the motherboard not being secured in the case). The outcome was the same: it eventually POSTed when flat but failed again once everything was correctly positioned and the case stood upright. Since this pattern keeps shifting depending on how the system is mounted, I’m more inclined to suspect a socket or motherboard fault rather than the PSU, though I haven’t completely eliminated that possibility.
Thanks for the feedback. I’ll proceed carefully as you outlined. So far, the issue occurs when the motherboard isn’t secured in the case and the system is flat, leading to a POST after some time. Once the board is properly seated and the case stands upright, the power cycle restarts. I haven’t yet tried the exact order you suggested—moving from no GPU and Wi-Fi to just the Wi-Fi card, then testing the GPU—but I’ll attempt those steps next to confirm. Regarding the socket pin, I’ll attempt a close-up photo to capture it clearly.
I'm curious if the issue lies with the motherboard itself or if it's caused by static electricity. Could you test it with another power supply? If not, I'd suggest re-seating all the cables. You mentioned you've already removed the motherboard from the case, so that should be covered.
You can refer to maps to understand the purpose of each pin. Some pins aren’t needed, others are unnecessary, and a few are crucial. We can’t be certain without knowing which specific pin is missing. Make sure to verify if any leftover pins remain in the socket and if they’re causing shorts with other pins.
I’ve disassembled the system once more and performed additional checks. I also captured several detailed close-up images of the CPU socket, which I’ve included below to aid understanding. I believe these should provide a clearer view of what’s happening. Upon closer inspection, it became apparent that the problem was more severe than initially assessed. There is one pin that seems missing or damaged, and another in the same column bent backward, making contact with an adjacent pin. This unintended connection likely triggered a short circuit, possibly explaining the erratic power cycling. I tried to carefully straighten the bent pin using a needle. While it moved into a more accurate position, its shape was distinctly different—lacking the typical inverted “L” form and instead appearing slightly concave. I attempted further adjustments with a needle and tweezers, but unfortunately, the pin tip broke off. At that stage, I took a moment to reflect on the situation. After that event, I thoroughly examined the remaining pins in the socket, and it appears they are all intact. I then reassembled the unit again (CPU, RAM, motherboard, PSU connected—no GPU or Wi-Fi card installed), hoping this would break the cycle of frequent power switches. However, before turning on the case power, I noticed some odd behavior: when I switched the PSU on at the back, the CPU fan twitched briefly, the intake fans flashed on and off, and the motherboard’s sound card LED pulsed. This occurred without pressing the power button. Ignoring that for now, I pressed the case power switch, but the same intermittent behavior resumed. Right now, I’m trying to figure out whether this is due to a failing PSU or a problem with the motherboard—especially the CPU socket and any damaged pins. At the moment, I don’t have a replacement PSU to test. Still, I’m inclined to think the issue lies with the socket or the motherboard itself. A few days ago, when the system managed to boot normally, everything was stable, and no PSU problems were present. Since then, I haven’t removed the PSU or made any changes there—just adjusted connections on the motherboard. I’m hoping these details and the photos will help clarify the situation. Thank you for your time and thoughtful responses; your insights are really valuable in helping me understand what’s happening.