I'm looking for a replacement to the noisy fans for a server 2U chassis. The front of the chassis is filled with the hard disks, which means that there is little space for air flow, which, in turn, means that I need fans with high static pressure.

The original fans have the following specification:

  • Rated current: 0.60 A.
  • Fan speed: 7,000 RPM.
  • Air flow: 72.5 CFM.
  • Static pressure: 27.69 mm/H₂O.
  • Noise: 53.5 dB(A).

The server will be heavily underused (storage only; CPU usage will remain relatively low), which means that the replacement fans can have one third the original static pressure value or ideally up to a half. So the requirements are:

  • PWM (4-pin).
  • Size between 80×80×25 and 80×80×38.
  • Static pressure superior to 10 mm/H₂O (or to 15 mm/H₂O).
  • Noise level inferior to 35 dB(A).
  • Price inferior to $40.

Generic fans such as Noctua NF-A8 PWM cannot be used. While the air flow is not bad (32.7 CFM), the static pressure is too low (2.37 mm/H₂O).

There is Silverstone FM81 which has an acceptable static pressure of 13.78 mm/H₂O, but it's also noisy at 48.0 dB(A).

What are my options?

  • I noticed you mentioned on Li Ming's post that your computer is fanless (at least in terms of the cpu). What about water cooling the CPU and ditching the case fans? The CPU is probably the biggest producer of heat in your computer, and I wouldn't expect HDD's to achieve unacceptable temperatures? – Bennett Yeo Jan 28 '19 at 23:15
  • Water cooling is indeed an interesting option, but for rack servers, it usually requires chassis which were made specifically for that, which is not my case. Unfortunately, I don't know a lot about water cooling, and paying a few hundred dollars to play with it and possibly discover that it won't work is not a solution for now. It could be a solution in the future, however. – Arseni Mourzenko Jan 29 '19 at 18:45

Have you tried Noctua NH-C14S low profile with 140mm fan:

Noctua NH-C14S, Premium CPU Cooler with NF-A14 PWM 140mm Fan

FAN specification:

  • Model 1x Noctua NF-A14 PWM.
  • Bearing SSO2.
  • Max. rotational speed (+/- 10%) 1500 RPM.
  • Max. rotational speed with L.N.A. (+/- 10%) 1200 RPM.
  • Min. rotational speed (PWM, +/-20%) 300 RPM.
  • Max. airflow 140,2 m³/h.
  • Max. airflow with L.N.A. 115,5 m³/h.
  • Max. acoustical noise 24,6 dB(A).
  • Max. acoustical noise with L.N.A. 19,2 dB(A).
  • Input power 1,56 W.
  • Voltage range 12 V.
  • MTTF > 150.000 h.
  • My apologies, my question wasn't specific enough. Servers usually don't have CPU fans; instead, they only have a heat sink, and are cooled through an array of fans which push the air from the front to the back of the machine (and not from the CPU towards the top/side depending on how you position the machine). 1U servers require 40mm fans. Mine is 2U, which requires 80mm fans. – Arseni Mourzenko Jan 27 '19 at 8:57
  • I don't think a downvote is deserved, because (1) the author could have been unaware of the specificity of rack servers (for a desktop PC of a size similar to 2U, his answer makes perfect sense), and because (2) many people on the blogs and forums do exactly that: put a low profile heat sink with a fan which blows the air to an immediately adjacent server cover plate, even if it means taking a risk of burning the CPU. – Arseni Mourzenko Jan 27 '19 at 21:29

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