Fujitsu PRIMERGY TX1320 M3 PSU planning Noctua NF-A4x20 PWM fan swap. Anyone done this before?

[Gruenschnabel]

I’m running a Fujitsu PRIMERGY TX1320 M3 with the 450 W Platinum Hot-Swap PSU (Fujitsu A3C40172099 / S26113-E575-V70 / S13-450P1A).
It works perfectly except the PSU fan is insanely loud (ofc cuz its a server psu fan).

What i know so far:

• PWM-controlled fan, tach required for PSU to start.
• Original draws 0.55 A, Noctua only 0.05 A — totally safe electrically.
• PSU gives a short 12 V full-burst at startup (Noctua can handle it).
• Alarm only triggers if rpm < 3500 or tach missing.
• PSU enclosure uses tight airflow → static pressure matters more than raw CFM.

PSU specs:

• 450 W 80 Plus Platinum, Hot-Swap, PWM-controlled fan, tach feedback monitored (fan-fail threshold ≈ 3500–4000 rpm).

My plan is to replace the Protechnic with a Noctua NF-A4x20 PWM (12 V / 5000 rpm / 5.5 mm H₂O / ~18 dB(A)). Same size, proper open-collector tach signal (2 pulses per rev), includes the OmniJoin adapter to crimp onto the original connector.

Pin mapping as i found it (1:1):

• Black → GND
• Yellow → +12 V
• Green → Tachometer
• Blue → PWM control (5 V, 25 kHz)

So my questions are:

1. Will the Noctua NF-A4x20 PWM actually work in this PSU? Has anyone here tried this or a similar fan swap successfully?
2. What could go wrong with this mod?
3. Any mechanical tips?
4. Would you cut the original connector and crimp using Noctua’s OmniJoin?
5. Are there any quiet but higher-pressure 40×20 mm 12 V PWM fans that outperform Noctua while staying under ~25 dB(A)?
6. Anyone with similar PSU experience?
7. Does this PSU include thermal shutdown / over-temp protection if airflow isn’t sufficient, or could it just keep running until something fries?

If you’ve modded or serviced these Fujitsu/Primergy PSUs or have fan alarm data, replacement experience, or tips about safety discharge time I’d love to hear it.

ChatGPT helped me formatting the thread.

TLDR: Change Server PSU FAN to Noctua FAN.