This Ubiquiti USW 24 Enterprise 24 PoE switch is truly great for my needs, but the fans .. so annoying, the high pitch noise they produce at a certain speed, just keep killing whatever brain cells I have left.
I have been monitoring the fan levels now for months and seems they float somewhere between 41% and 54%. The annoying part hits somewhere around 47% and actually goes away above 50%
So I thought, I'd replace them with two silent Noctua NF-A4x20 PWM (40x20mm) fans, I know the airflow is not the same .. not even close, but monitoring the temperatures and fan levels for some months now, I am quite sure these are enough.
Opening the case
Remove the rack ears to uncover all the screws that hold the top cover in place. There are 7 screws in total. (You don't need to remove the front panel screws.)
Slide the cover back, there are "lips" that go under and over the front part
Lift the cover off
Removing the fans
First detach the POE cable, that gives better access to the screws and fan cables under it.
Detach the two fan cables
Unscrew the 6 fan cover screws
After that, you should be able to carefully pull up the cover.
Unscrew the fan screws and pull off the old fans. The cables are taped in two places so you need to remove that temporarily.
1 m³/h = ~0.589 CFM | 1 CFM = ~1.699 m³/h
1 m3/h = ~0.0166 m³/min | 1 m³/min = 60 m3/h
According to the specifications, the Noctua NF-A4x20 PWM is capable of 9.4 m3/h, which translates to roughly ~0.157 m³/min, or 5.5 CFNM. So on the paper, the Noctua fans do not match even close to the airflow produced by the original fans.
Installing new fans
Slide in the new Noctua fans, the fan grills facing inward towards the PSU (the fans are blowing air in that direction). Check that the cables are not stuck too badly or do not obstruct the airflow.
The old fan screws do not fit, so use the ones that came with the Noctua fans. Also the fan headers are a little bit different.
- Reattach the fan cover, and check that cables are not pinched from any side.
- Screw-in the six fan cover screws
- Attach the fan cables: I had to use the Noctua extension cables to get the cables reattached, the fan headers are not exactly the same, so you will need to slice off one of the plastic tabs (of the extension cable heads that attach to the board). Otherwise, it fits in place fine.
- Attach the POE cable!
- Slide the top cover back
- Screw the 7 top cover screws back-in
- Attach the rack ears
Restarting and monitoring
So far the temperatures seem to hold at 44-45 degree Celsius, and the fan level is around 45 - 50%, but noticeably silent.