DNS-320L overheating after installing a Noctua NF-A4X10-FLX 5V fan (not an Alt-F problem as such)

[Guillaume Veys]

Hello ! I've got a DNS-320L that was too noisy so I went and bought (and installed) the Noctua NF-A4X10-FLX 5V.

I followed the indications from that thread : https://groups.google.com/d/topic/alt-f/6mOTWKBMI_4/discussion

(Basically, it says that the red and black cables should be inverted; I did that and the fan runs smoothly and silently.)

If you want to do it, there's a video here: https://youtu.be/KSXcZSvZsZY

Because of the way the fan is designed, and especially the screw holes (in the fan), I had to flip it and now the NAS' temperature reaches 45°C 🌡 instead of ~33°C and the fan is always at 6000 rpm. I not, the screws are too short and I'm pretty sure if they weren't I couldn't close the box.

Has anybody had and overcome this issue? I'm fairly confident the problem is the fan's orientation (the air goes the wrong way).

Any ideas?

As I said in the title, it's not a problem with Alt-F but I'm posting it here because I think it can help the community (and me 😉)

Thanks. 😀

[Guillaume Veys]

I didn't want to do it because it probably voided my warranty but I decided to enlarge the screw-holes' entry to solve the problem.

I don't like it but it does the job. Now I'm waiting to see if the temperature goes back to normal....

[Paul Wilkie]

As a DC fan, reversing the cables should reverse the direction of rotation, so maybe you should have left the cables as original and flipped the fan.  The spec for this fan gives a maximum speed of 4500 rpm.  Thanks for posting as I have been thinking about looking for a quieter fan myself.

[João Cardoso]

On Saturday, 20 June 2020 14:58:05 UTC+1, Guillaume Veys wrote:

I didn't want to do it because it probably voided my warranty but I decided to enlarge the screw-holes' entry to solve the problem.

I don't like it but it does the job. Now I'm waiting to see if the temperature goes back to normal....

Le samedi 20 juin 2020 15:19:00 UTC+2, Guillaume Veys a écrit :

Hello ! I've got a DNS-320L that was too noisy so I went and bought (and installed) the Noctua NF-A4X10-FLX 5V.

I followed the indications from that thread : https://groups.google.com/d/topic/alt-f/6mOTWKBMI_4/discussion

(Basically, it says that the red and black cables should be inverted; I did that and the fan runs smoothly and silently.)

To complement Paul's post:

The air flow should be outward the box, to exhaust internal hot air to the exterior. The top cover should be closed and not covered by anything. There should be a small clearing space around the box.

On the DNS-320L the only fresh air intake is from the many small holes around the top cover, but my experiments showed that without the top cover in place the fan does nothing, as cold air does not reaches the box bottom, where the electronic circuit main board is located; the box bottom has no fresh air intake. In my opinion a bad thermal design.

correction: There are air intake holes in the bottom, but the internal circuit board is tightly adjusted to the case, so no air can pass between them, so there is almost no air intake from the box lower holes.