[SOLVED] NHD15 fans stop spinning momentarily

[tarogmats]

So I bought the D15 for my system set it up, saw a pretty decent decrease in temps overall and under load, but I noticed the outer fan that I could see, would slow down sometimes. I chalked it up to the system controlling it, because I didn't adjust any of the CPU fan settings and instead left those up to the system.
Booted from sleep this morning, and I noticed the fan would spin and stop, spin and stop, it'd spin for a good couple seconds, then stop. So I checked the interior fan as well that's in the middle of the cooler and realized that was doing the same thing, they were operating in unison.

So is this a default setting, is this normal? Or is there something wrong with the fans.

mobo is a b450-f gaming ii
cpu is a 2600x.

 

[avg9956]

The Noctua NH-D15 CPU Air cooler has 2 fans. You can opt to install either 1 fan or 2 fans onto the CPU cooler. I have it too but only installed 1 fan and still decent enough to cool my CPU temps. I couldn't install the 2nd fan because RAM was in the way so I plan for it to be the replacement fan when the 1st one breaks down (and they last for a very long time).

My guess is that the fan settings in your BIOS for the CPU Fan needs to be changed to PWM mode and not VDC, otherwise I would test out those fans by connecting it to another system and see if the behavior is replicated. If the behavior is the same, then the problem is with the fans.

 

[geofelt]

Check your bios fan settings.
A fan needs sufficient voltage to start(5v), that would be likely at 500 rpm.
Noctua supplies a splitter to connect both fans to the cpu fan header so they can be both controlled in the same manner.
The fans are very quiet, they are all but inaudible up to 900 rpm.
You can start them higher.

 

[tarogmats]

- late response, thanks for the input.
The fans were fine, it was the default setting in bios. I was used to my fans being on constantly because of the temp. But the cooler was much better so lower temps = fans cycling down.

 

[Paperdoc]

As far as I'm concerned, NO CPU cooling fan should ever STOP. But any such fan does have a minimum speed. IF your control system sends it signals to run slower than that, it may well stall. When that happens it will NOT re-start until the control system sends it signals to run significantly faster so that it can actually re-start. Now, the fans on that unit are PWM-style fans, and they can be run a bit slower when controlled that way. BUT if you set the CPU_FAN header to use DC Mode, there is a greater risk of the fan stalling at low cooling needs.

BEFORE going further, a note about Noctua's LNA's (Low Noise Adapter). These little units can be placed in the fan's power connection to reduce the fan speed by reducing its Voltage supply, but of course that also reduces significantly the cooling provided. Further, it WILL reduce the power supplied to the fan in low-speed situations and may be part of your problem IF you used it. Really, the LNA is useful ONLY if your fan is connected to a constant 12 VDC supply directly from the PSU - then the only way you have to reduce speed is with the LNA. When you use an automatic fan control from a mobo header, do NOT use the LNA.

Some mobos have a configuration setting for minimum speed for their headers, but your does not. You DO have a way to accomplish this, though. See your mobo BIOS manual p. 12 where it detail setting your own "Fan Curve" of what speed to run a fan for what measured temperature. Before making any changes here, look at the previous page. In BIOS Setup go to that screen and ensure that, at the bottom, you have chosen "Standard" automatic control, which is how you say you have been using it. NOTE the minimum speed set for the lowest temperature, which is likely causing your fans to stall. Now, choose instead the "Manual" control option at lower right, then go to p. 12. Use your mouse to drag the setpoint for the lowest temperature and speed to a higher minimum speed. Use the Esc key to return to Main Menu, then F10 to get to the Exit Menu (p. 81) There Select Save Changes and Reset to save your settings and reboot. See if that prevent the CPU cooler fans from stalling.