Question Fan has a mind of it's own

Canadacpu

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Jul 11, 2016
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Hi All,

Hoping someone can help me out here.

I just built a new Ryzen PC and am having some issues with fans.

Mobo is a Gigabyte X570 Aorus master and the fans are Corsair 140ML Pros.

Issue #1: The fan plugged into the #5 fan header (also a pump header by the looks of things) appears to have a mind of it's own. It will ramp up to max speed with the slightest change in PC activity despite being manually locked to ~800 RPM in the BIOS. While I am still in the BIOS, it appears to behave. Once I am back in Windows and actually using my PC, nothing I can do seems to settle this fan down to a constant RPM. If I play a game it will ramp up to full 2400 RPM which is extremely loud. All other fans work as expected when set up identically to a set RPM. The only difference is this is also a pump header, so that may have something to do with it but I don't know what that might be. I have also tried setting it to PWM and making a custom curve but it does nothing to help. All fans are set to the same sensor point.

Issue #2: I use HWMonitor to help confirm fan speeds, and it reports incorrect fan speeds for some of the fans (approximately double the RPM). I know they are not running that fast as they are near silent as intended vs. sounding like a jet engine. Is this just a HW Info bug or is there something I can do to make this more accurate? It reports some fan RPMs perfectly and others are way off. It also does not report a #5 fan header speed, but it shows duplicate "FANIN2" data points, so I assume one of those is my #5 header but it's unclear.

Thanks in advance!
 
Last edited:

Ralston18

Titan
Moderator
Update your post to include full system hardware specs and OS information.

Include PSU: make, model, wattage, age, condition.

Issue #1.: Swap the fan with another one of the fans that "work as expected". Determine if the problem follows the fan or stays with the #5 fan/pump header.

If the problem stays with the header then look at the cables, adapters (if any) for other opportunities to swap about with respect to the fan header.

Issue #2: First determine and, if at all possible, resolve Issue #1. If Issue #1 is resolved, Issue #2 may become moot. Otherwise with too many changes, etc. you may end up going in circles.

As you try things with respect to Issue #1, keep an eye on what happens or changes via HW Monitor. You may find some link or clue as go along.
 

Canadacpu

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Jul 11, 2016
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Thanks for the reply. Good idea to isolate the problem to the fan or the header - I will give that a try.

OS is Windows 10 Pro.

Hardware:

Gigabyte X570 Aorus Master
Ryzen 5950X CPU
32GB 3600Mhz Trident Z Neo Ram (2X16)
1080Ti
Samsung 980 Pro 1TB SSD
Corsair AX860i PSU, new condition, Seasonic OEM. Total system draw under load is under 500W so there is plenty headroom there.

Can I unplug my fans and plug them back in while the system is running without hurting anything? That would be a heck of a lot easier than shutting down for each test.
 

Canadacpu

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Jul 11, 2016
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Funny story - I accidentally hit the clear CMOS button on the back of my PC while moving it, which caused me to have to reset everything in the BIOS. After doing that, the fans can now be controlled as I expected and are working fine as best I can tell.

HW info still reports RPMs that are definitely inaccurate, so I am not sure what's going on there as I am pretty confident all my fans are no working as they should via the BIOS fan control.
 

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