Loud Fan NV4108-HS

[AaronG]

The fan is quite loud. Much louder than my PC with my GTX1080ti, water cooling, full tower. The video below doesn't quite do it justice, but the Hz that it outputs is very noticeable.

When I remove the top cover, it is nearly silent. I cannot hear it when I am more than 2 feet away, and when I get close, it is just a quiet little motor. Put the cover on and it changes harmonics completely. Is this due to air restriction? Would removing that grill with the holes resolve the issue? It doesn't seem that it is an output issue as there are lots of various fins around the case to let air out. I'd believe it was input pressure. Should I reverse the fan to a blower style (output)?

https://www.youtube.com/watch?v=vkrO71XrWDc

[plusfour]

If the noise is caused by the grille rather than the fan (and it's astounding how loud it is on mine), has anyone considered cutting away the grille? I was going to get a quieter 40mm fan, but if most of the noise comes from the grille it may make more sense to remove that instead.

[mikedj]

I tried turning the fan around on mine and it made no difference. Removing the grille might help, but poses the problem of something hitting the blades of the fan and stopping it (as my finger did a time or two while messing with it). I've seen some YouTube videos of people buying quieter fans. I thought about ducting it to a more internal location, but haven't tried it yet.

Mike

[plusfour]

Yeah, there are assorted quiet(er) 40mm fans around, but if the noise is from the air being pushed through the grille it won't really help much. You can get far less intrusive 40mm wire fan covers to replace the punched-metal grille:

https://www.ebay.com/sch/items/?_nkw=40mm+fan+cover

that will keep fingers and whatnot out while reducing air resistance and noise. I'll pull mine apart maybe tomorrow and report back on what's causing the noise, but I suspect it's mostly the grille. You can actually hear it directly, hold a finger in front of the grille and the noise level goes way up as even more resistance to air movement is introduced.

[Z-Man]

I disconnected the fan in mine. It was too loud for my taste. However, I do have the NVR in a well ventilated area and there's plenty of room around it (under, above and to the sides).

[plusfour]

So the problem with the fan noise is a combination of three factors:

• Inherently loud fan.
• Fan grille that significantly impedes airflow.
• No temperature control, so the fan is always running at full power.

To deal with the second issue, I've cut away the fan grille:



which made a noticeable difference, it's gone from dentist-drill-like whine as soon as you put your head inside the room to something where you have to stand in front of the cupboard where it's located to hear it. It's still loud, but nowhere near as bad.

Next step is to replace the fan with something quieter.

[plusfour]

So the fan in mine is a Sunon HA40101V4, which is this and this.

According to the second data sheet it's a vapo bearing fan, 40mm, 12V, super low speed, 15.7dBA. The "Super low speed" rating is a bit difficult to reconcile with 5000rpm, and I'm getting a reading of 40dB about 5cm from the side of the fan, and close to 50dB with the microphone held as close as possible to it while trying to minimise interference with airflow. Sunon's measurements were taken 1m from the intake in a semi-anechoic chamber, I'm getting about 28dB in my uncalibrated non-anechoic cupboard at the same distance.

It looks like Amcrest/Dahua have tried to put in a quiet fan, but the fan is anything but. Next step is to try a different fan, I'm currently weighing up whether I should try a generic FDB fan or spend a pile extra for a Noctua, particularly the FLX which allows manual speed control so I can take it down to 3700rpm in the absence of PWM control by the NVR.

[mikedj]

Thanks for posting the detailed report. Let us know how the fan(s) work out.

I also wonder just how much cooling is needed. Have you made any temperature measurements?

Mike

[scoutermac]

I'm sure there are many factors to how much cooling is needed. Such as how many cameras you are using and how often they are recording. Also how warm or cool the environment that this NVR is located in. If I purchase this unit I am considering placing it in a closet to keep it out of view and out of hearing.

[plusfour]

Thanks for posting the detailed report. Let us know how the fan(s) work out.

I also wonder just how much cooling is needed. Have you made any temperature measurements?

I suspect a lot less than they're actually using, but they have to deal with a worst-case situation, NVR in a hot closet running continuous recording on multiple cameras. In my case it's in a relatively cool area with motion-trigger recording only, to an SSD, so the least possible heat output from the electronics.

OTOH even the most trivial amount of airflow from forced-air cooling can make the difference between impossible-to-track-down glitches and errors and correct operation, so running with no airflow at all seems risky. Next time I crack the case open I'll get some photos with a thermal imager, however it won't be a totally accurate representation because it's dependent on the outside environment, having the case closed, and having the fan running or not running. However, if temps are close to ambient I'll feel a lot more comfortable running a Noctua at its lowest possible setting for cooling. A 5000rpm fan seems a bit excessive in any case.

Another option would be to use Linux' built-in thermal monitoring, but the NVR is pretty well locked down, no unnecessary services running so access will require a bit more than just SSH-ing in using a password reverse-engineered from the binaries.