[SOLVED] CPU Fan Error, everything else works fine

[Nate_30]

As the title says, I'm encountering a strange issue. My PC has worked fine since I built it in late 2019, and this is it's first big issue. Seemingly overnight, the CPU fan has stopped functioning. I see it start to spin upon power up, then it just stops. Sometimes it tries one more time, but it always stops and never spins again unless I turn it off and on again, only to fail again. This causes the CPU Fan Error message to appear. I've tried cleaning the entire PC, I've replaced the fan itself, and I've tried resetting the BIOS settings. Nothing has worked. Other than this problem, the PC has no issues. Every other fan works, the lights are on, and the PC recognizes every component, except for the CPU fan. What should I do?

Specs:
CPU: Ryzen 7 3700x
CPU fan: Noctua NH-D15S chromax.Black
GPU: RTX 2080 TI
RAM: Corsair Vengeance RGB Pro 32g (4x8)
Motherboard: ASUS Prime X470-Pro

 

[Nate_30]

Before getting too involved try free things first. May be it is the fan header, try plugging a known good fan into the fan header that the CPU is using. If the good fan fails to turn the header is bad. Try your old CPU fan in a known good header and see if it works, the old fan may still be good. If the CPU fan header is bad try a different fan header, go into BIOS under fan settings and for the new header that the CPU fan is now using, turn the fan speed up to 80% or something you are comfortable with. While you are in BIOS, check to see if the original fan header for the CPU has been turned off. If the power cable for the CPU fan is too short to reach a different header, you can buy an extension for very little.

Can confirm that my CPU fan is now working. Plugged it into the CHA3 FAN header and works perfectly. However, I'd still like for my previous questions to be answered since this feels more like a temporary solution. Thank you so much!

 

[mikewinddale]

Running your CPU fan off a chassis header seems like a fine long-term solution. This isn't worth replacing a motherboard over.

If you run out of fan headers, just use a few Y-adapters. As long as the collective wattage of the fans doesn't exceed the wattage of the headers (12W per header; see your manual, page 1-14), you'll be fine. A typical fan uses about 1W (see the specifications for your fans), so you should have no problems running multiple fans off a single header with Y-adapters.

You could also use a PWM-aware fan hub.

Asus gives instructions here on how to disable the CPU fan error by setting it to "ignore."

 

[Nate_30]

Running your CPU fan off a chassis header seems like a fine long-term solution. This isn't worth replacing a motherboard over.

If you run out of fan headers, just use a few Y-adapters. As long as the collective wattage of the fans doesn't exceed the wattage of the headers (12W per header; see your manual, page 1-14), you'll be fine. A typical fan uses about 1W (see the specifications for your fans), so you should have no problems running multiple fans off a single header with Y-adapters.

You could also use a PWM-aware fan hub.

Asus gives instructions here on how to disable the CPU fan error by setting it to "ignore."

Thank you very much. I appreciate all the help I've received, glad to say that my CPU fan is working perfectly again, and hasn't even passed 70c under a torture test. Thank you!

 

[DRagor]

That's a well known workaround for this kind of problem. However, there is one catch: now you don't get the warning when the fan fails (because that only works on CPU_FAN header). As a safety precaution I would advise running any temp checking software and monitoring CPU temperature this way.

 

[Danra]

Thank you very much for this suggestion, however I have a few questions. If something does go wrong with the fan in the future should I plug in the CPU fan into another header, will it still give me the same warnings and alerts that the main CPU fan header would have? Can I set the same fan curve for it in a header different from the dedicated fan header? Are there any other unforseen consequences from using an alternate header for the CPU fan that I'm not thinking of? Will I have to disable the CPU fan error triggers in order to bypass the error should I use a different header? Is there truly no way that the PSU is responsible for somehow shorting out these headers, and that it could do more damage to others? Thank you

A different fan header than the CPU_FAN and CPU_OPT [they are shared] will not give you the same warning as CHA-FAN 1, 2 or 3. If the CPU gets too hot the computer will shut down, however I don't like to trust an over heated CPU to tell me the fan failed. Using a chassis fan should be a stop gap measure until you can get another motherboard. A good fan will last several years, Noctua guarantees their fans for 6 years for example. The fan curve [speed] on your motherboard, according to the factory, is adjustable. The chassis fans CHA_FAN 1, 2 and 3 yield the same voltage as the CPU fan header, so there is no issue, it will not damage your fan. You will need to bypass the CPU fan warning in order to boot into Windows. A weak or otherwise faulty PSU can destroy any electrical component in a computer.