Changing the 120 fan of my SX700LPT for the Noctua nf-a12x15-pwm

Kyuss

Chassis Packer
Original poster
Jul 13, 2017
17
5
Hi!

I bought a Noctua NF-A112x15-PWM fan to replace the crappy Poweryear PY-12015H12S that comes with the SX700LPT PSU. I made a quick test yesterday connecting the red wire from the old fan to pin2 (+12V - yellow) in the Noctua and the black wire (old fan) to pin1 (Ground - black).

I tried using the Heaven Benchmark in order to get the 150-200w threshold to trigger the fan but it doesn't spin. I think the connections are OK and the PSU can move the Noctua but I don't know why not.

The specs of the fans are:

Noctua / Poweryear
Max. Input Power: 1,56W / ?
Max. Input Current: 0,13 A / 0,22 A
Voltage: 12 V

Any help?
 

VegetableStu

Shrink Ray Wielder
Aug 18, 2016
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I'm not good at electronics of this level, but I'll go have a look if the label says anything about minimum power-on voltage for both fans

did you notice the noctua fan jiggle once when you were running the benchmark?

EDIT: no official listing on poweryear's site (but the 120mm fans are all 5V minimum), and notcua doesn't specify firsthand

They did mention this though:
Different starting voltage: Most network devices use voltage-based speed control. If the new fan has a higher starting voltage than the original fan, it may not start up right away. This may lead the device to display errors or even shut down because it suspects a fan failure.
 
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Kyuss

Chassis Packer
Original poster
Jul 13, 2017
17
5
I'm not good at electronics of this level, but I'll go have a look if the label says anything about minimum power-on voltage for both fans

did you notice the noctua fan jiggle once when you were running the benchmark?

It doesn't move at all, BUT it wants to. When I move the blades it moves more than if it were not connected, so it seems that is drawing some current but not enough to begin the movement.

I can not find any info about the Poweryear garbage, even in it's website.

I think I am going to connect the Noctua to the MB, it's not elegant but it sure works.
 
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VegetableStu

Shrink Ray Wielder
Aug 18, 2016
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just to check two things to understand more:
  • how are you measuring system power draw?
  • does your PSU's serial number start with 1624?
EDIT: the fan controller's voltage-based, so maybe the lowest point isn't enough to wake the noctua fan? Again, Noctua doesn't state where this number starts

I think I am going to connect the Noctua to the MB, it's not elegant but it sure works.

I did exactly this, LOL
 
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EdZ

Virtual Realist
May 11, 2015
1,578
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From SFFnet's very own review:
Since there is no information to be had from the manufacturer or anyone else, I tested the voltage/RPM fan curve myself. The fan’s starting voltage is 2.6V, and from there it’s a fairly flat curve up to the max RPM of 1910 RPM at 12V. The fan exhibits no strange behavior at the starting voltage, once it gets to 2.6V it starts up and that’s it.

A later revision shifted fan spinup to lower power loads but would need to have kept the same startup voltage (as that's a property of the fan).

I'm not sure of Noctua publish voltage curves - or starting voltages - for their fans (can't find one with a cursory Google) but even if they do, then you need to look at voltage vs. airflow rather than just voltage vs. RPM, as it's no good matching RPM-for-RPM if you;re only getting half the airflow.
 

VegetableStu

Shrink Ray Wielder
Aug 18, 2016
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6V vs 2.6V. I think that might be it o_o

there's not enough of a load to get the PSU sending more voltage to the fan to even get it spinning, it seems
 

GREENPROTAG

Minimal Tinkerer
New User
Aug 19, 2019
3
0
Any luck on this project?
I am very tempted to swap out the stock fan for a Chromax Noctua or a solid spec fan with illumination.