Nocutua fan speed

[markTT]

Hi all

I read the comments on the PSU upgrade posts and thought I'd add a few bits about the Noctua fan and its speeds. I performed the upgrade today on a PSM-5341 -001 in my Atari TT which had a Nidec BETA SL Model DO6T-12TH fan (I don't know if this was original or not). Airflow direction arrow was from in to out. The replacement fan is a Noctua NF-A6x25 FX.

The Nidec BETA DO6T-12TH is rated at
0.1Amp 3060 RPM displacing 14.13 cfm [24.3 m3/h] at 23 dBA

The Noctua specs are
w/o adapter 3000 rpm 29.2 m3/h 19.3 dBA
with low noise adapter (NA-RC10) 2400 23.5 m3/h 14.5 dBA
with ultra low noise adapter (NA-RC12) 1600 16.7m3/h 8.2 dBA

The Noctua with the low noise adapter gives slightly less airflow than the maximum of the Nidec. Both are rated with a power draw of 0.12 Amps.

[exxos]

Is there CFM specs for the Noctua fan ? Would be easier to understand what is going on then I think :)

[stephen_usher]

Remember that the TT fan pins have the opposite polarity to those you expect as it has -12V and 0V on the connector.

From experience Noctua fans are required to run at full speed to adequately cool the TT power supply. They are still very quiet but not totally silent.

[mikro]

Indeed. @czietz just recently posted a very convincing visual proof how much the fan is needed: https://www.atari-forum.com/viewtopic.php?t=42737

[markTT]

Is there CFM specs for the Noctua fan ? Would be easier to understand what is going on then I think :)

I put the m3/h equivalent for the original fan to make the comparison. The calculation was made thus
a = z / 0.588578

Where,
a = Cubic Meter/Hour Value
z = Cubic Foot/Minute
or more simply - https://www.easycalculation.com/unit-co ... ulator.php

Remember that the TT fan pins have the opposite polarity to those you expect as it has -12V and 0V on the connector.
From experience Noctua fans are required to run at full speed to adequately cool the TT power supply. They are still very quiet but not totally silent.

Thanks Stephen. Yes, I took into account the polarity which is wired up correctly and working fine, blowing air out of the back of the PSU as per the original design. From comparing the component specifications, the Noctua running at 2400 rpm - the low noise setting will give the equivalent of the original fan.

Unfortunately I don't have a thermal imaging camera to make a heat comparison, between stock and Noctua at 2400 rpm. After running for 8 hours yesterday on a stock machine with the case back together, and light usage I have not noticed any abnormal heat in that area.

The intent here has been merely to provide a comparison of the airflow specifications between a stock and Noctua fan. They show clearly to avoid the ultra low noise setting at 1600 RPM and there should, on paper be no discernable difference to a stock fan and Noctua at 2400 RPM - the low noise setting. It also shows that running at 3000 rpm will give improved airflow which may be of benefit for e.g. a machine with different addons and expansions, or simply for better peace of mind.

[Steve]

Yes I would run at full speed personally, for extra protection.