[SOLVED] CPU Fans and Headers: CPU Fan Error Story

Aug 4, 2020
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I just wanted to share my strange story as I couldn't find anything online that helped me. I hope this may help others.

I recently installed an Enermax LIQFUSION 360 in my computer and everything for over a week or so was doing just fine. This wasn't my first install of an aftermarket CPU cooler or additional fans. Last night, after trying to power the computer up, I got a message in post saying CPU Fan Error. The CPU fans weren't spinning at all, and there weren't any signs of anything stopping the fans, the fans were still clean, etc. I tried moving the fans from the first header to the second header (CPU_OPT), but the computer wouldn't recognize the second header as being the CPU fan. I figured that since there wasn't a fan plugged into header 1, that the computer didn't see header 2, or it just needs header 1 to have something in it to consider that there's a CPU fan (which is odd as I had the CPU fans plugged into header 1 and nothing was working). I plugged the fans back into header 1, got the CPU error, then went into BIOS and reset back to optimized (factory) settings to clear out anything that could give me errors.

The computer was then able to boot, but the fan speed never got above 25%. This could be an issue with higher CPU demand, and something wasn't working the way it should, so naturally I had to fiddle with it more. Since it was kind of working, I figured, well maybe we can try plugging one fan into header 1 and two fans into header 2. Good news, the header 2 fan was spinning really fast, but the header 1 fans were still very slow. I tried to plug the fans all into header 2, but again, CPU Fan Error... Since my fan was spinning faster on header 2, and I could scale it up/down in my fan controller software, I thought to plug all the fans back into header 2, but then unplug my rear case fan from it's header and plug that instead in header 1. Again, the thought process being the motherboard thinks that nothing is plugged in for a CPU fan unless header 1 has something on it, and it shouldn't matter if it's a different fan as header 2 has the actual CPU fans plugged into it.

Computer booted, worked great. Fans now scale up/down as they should and I can set the header 1 fan (back fan) to whatever I want and header 2 fan (CPU fan) to whatever I want.

tl;dr version:
If your getting a CPU Fan Error, and your fans are working, try plugging your CPU fan(s) into header 2 and then plug your rear case fan into header 1 and boot. Recalibrate your fans in your fan controlling software or BIOS and you might be good to go. If it's still giving you issues, reset BIOS to optimized/factory settings and reboot.
 
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Aug 4, 2020
3
1
20
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Mods, can you flag this as "Solved" and tag the OP?

Copied from above:
If your getting a CPU Fan Error, and your fans are working, try plugging your CPU fan(s) into header 2 and then plug your rear case fan into header 1 and boot. Recalibrate your fans in your fan controlling software or BIOS and you might be good to go. If it's still giving you issues, reset BIOS to optimized/factory settings and reboot.
 
Last edited:
Aug 4, 2020
3
1
20
1
Mods, can you flag this as "Solved" and tag the OP?

Copied from above:
If your getting a CPU Fan Error, and your fans are working, try plugging your CPU fan(s) into header 2 and then plug your rear case fan into header 1 and boot. Recalibrate your fans in your fan controlling software or BIOS and you might be good to go. If it's still giving you issues, reset BIOS to optimized/factory settings and reboot.
 
Last edited:
Aug 4, 2020
3
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Updated story:

So I had some issues where ASUS' Fan Expert couldn't find the front fans that were inside my case. I reset the settings in the BIOS again to optimized, but it didn't fix it. Since I had everything apart, I figured I'd try resetting the CPU fan back to where it was originally in the CPU1 fan header and plug the back fan on it's normal header. I booted and went back into the BIOS and set the front fans to DC mode and the CPU to PWM mode. Both the front fans and CPU fans are 4-pin and the back fan is 3-pin. Saved/booted and Fan Expert can see the fans and control them via that software again. All working ok once more.

Note: I saw a lot of forum posts that 3-pin fans should be set to DC and 4-pin fans should be set to PWM. However, if you're still having issues, try switching the settings to the opposite. I saw one person who had 4-pin fans set in DC mode, but was still able to control the speeds in Fan Expert.

Shorthand: maybe you can go into your BIOS and try setting your fans to either DC or PWM modes and trying to boot. Your motherboard might just be confused with the fans, and that could be causing the error.
 

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