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158 days after I built my computer, the CPU fan that came with my SilverStone AR06 died (it could not spin fast enough to cool the CPU. Manually setting the fan speed to 100% wasn't helping). So, I bought a Noctua fan to replace it. 329 days later, my Noctua fan failed. The fan was working when I turned the computer off. The computer stayed turned off for a month. Now the fan will not spin. It barely spins when I power it up, but that's about it. I blew on it a bit, and rotated it myself before turning it on, which caused the fan to barely spin for a few seconds, before coming to a stop again.

There's not much to see, but here it is attempting to run when I turn it on: https://youtu.be/xwJGs7zjkYU

I tried a different fan header, but that didn't produce any different results.

I find it extremely unlikely that two fans would fail... especially a Noctua. At this point I suspect the motherboard might be to blame, but I'm not sure. Should I replace the fan yet again? Is the motherboard at fault? What should I do to further troubleshoot? I'm afraid to leave my computer on for too long (i7 6700k) without a working CPU fan. Am I just really unlucky?

Here I managed to get the fan to run extended (flipped the computer on its side): https://youtu.be/Qn6y1HWLkII. It's still definitely not spinning fast enough to do much.

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  • It's possible the motherboard fan header is delivering insufficient power to the fan. Are you able to connect the fan to another computer or some arbitrary 12V source to see if it will spin up? The NF-A9 PWM (which I'm assuming you're using given the heatsink specified) only uses 0.1A, so there's no reason it would overload the board. Noctua fan failures are extremely rare, so it's vastly more likely that the motherboard is at fault.
    – bwDraco
    Jan 8, 2018 at 21:37
  • Judging from your videos, it looks like insufficient power is getting to your fan. Does it spin freely when you try to move it yourself, and are there any noticeable noises from the bearing? If you have a multimeter, what's the voltage on the fan header? Also, the fan is mounted incorrectly—the Noctua label should face the heatsink so that it blows air towards the heatsink.
    – bwDraco
    Jan 8, 2018 at 21:50
  • Fan spins freely if I move it myself. I've tried both orientations of the fan, and this way seems to work the best. Though if my fan is not getting enough power, I'm not sure what to think. Could a bad setting in the bios be causing this?
    – MrZoraman
    Jan 8, 2018 at 21:53

3 Answers 3

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While you found the solution to your problem, that doesnt answer the question you asked: Can a faulty motherboard kill the CPU fan?

The answer is that it is extremely unlikely. Fan headers on motherboards run off 12v. That 12v is supplied by the 12v line from the power supply unit. If the 12v line was delivering too much or too little power, you would be having other far more serious issues with your computer.

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The fan behavior I'm seeing in the video suggests that the fan is receiving insufficient power.

If the fan is set to DC mode, change it to PWM mode. These fans are designed to be controlled by a PWM signal with which the fan's built-in motor controller automatically adjusts the speed, and should always be receiving 12VDC. DC fan control reduces the fan voltage to slow down the fan, which is less accurate and may cause PWM fans to malfunction, though Noctua fans are supposed to be well-behaved in this situation. (edit: according to page 14 of the motherboard manual, the CPU fan header is PWM-controlled while the chassis fan header is DC-controlled.)

If this doesn't work, I'd try hooking up the fan to another system to see if it runs and/or probing the fan pins with a multimeter to determine if it's outputting the proper 12VDC (be very careful not to short the pins when you do this). Motherboard fan headers can and do fail even with properly functioning fans, causing them to deliver insufficient power or no power at all.

Also of note is that your videos show that the fan is blowing outward, and, as such, is incorrectly installed. The fan should be installed with the Noctua label facing in so that the air is blown into the heatsink.

Ultimately, I would suspect faulty fan headers, which would require replacing the motherboard. It is extremely rare for a Noctua fan to fail in this fashion; if it does happen to be the fan, there's a 6-year warranty on it so it should be easy to get it replaced.

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  • How do I switch between DC and PWM mode? My fan has 4 pins, and the fan header has 4 pins, so I think I'm already in PWM mode. Or is there a switch/setting or something I should look for?
    – MrZoraman
    Jan 8, 2018 at 22:05
  • There's should be a motherboard fan control setting that lets you change it. By default, it should be PWM, but it's not impossible for it to be in DC mode. I'm not too familiar with the Gigabyte BIOS interface, though; can you tell me what model board you're using?
    – bwDraco
    Jan 8, 2018 at 22:07
  • gigabyte.com/Motherboard/GA-Z170N-Gaming-5-rev-11#ov Even if it is a motherboard bios setting, can I get into the bios and change the setting before I fry my cpu?
    – MrZoraman
    Jan 8, 2018 at 22:11
  • A look at the manual (page 14) indicates that the CPU_FAN header is PWM-controlled while the SYS_FAN header is DC-controlled. I don't see a way to set that in the BIOS. Of note is that modern CPUs are smart enough to throttle themselves if they overheat; the heatsink will buy you some time.
    – bwDraco
    Jan 8, 2018 at 22:17
  • Thank you for your help. I guess I'll see if I can get my hands on a multimeter sometime this week and I'll see what power these fan headers are supplying. Is it also possible that this is a power supply problem? (Power supply not giving the motherboard enough power)
    – MrZoraman
    Jan 8, 2018 at 22:25
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The fan was on the wrong way. I guess the fan was being pressed against the heat sink, making it hard for it to spin. Flipping the fan around seems to have it working properly.

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  • Yeah, while a broken motherboard CAN break or prevent a fan from working, improper installation is always a more likely culprit. Don't worry, it happens to the best of us, which is why every guide says to check these things first. If the fans aren't spinning up, power them down and give them a little spin with your finger to check them in the future. There are spacers gaskets and shims you can install if the fan needs a little space. Feb 4, 2020 at 6:34

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