Question Anyone using Noctua NF-A12x25 fans? Are they really as good as they say?

Jan 9, 2020
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Hi all,

I recently changed the fans on my old Noctua NH-D14 to 2 x NF-A15 PWM. Pretty happy with the temps and noise and price etc. However, the more I read about the NF-A12x25, the more convinved I am that two of those would perform even better on this, and possibly also on the NH-D15 heatsink. On paper, the airflow on the 120mm A12 is only about 10% worse than that of the 140mm A15, but the pressure rating is about 50% better. The price is high, of course, it doesn't make financial sense to get these for my old cooler, but for tinkering purposes perhaps.
I can't wait to see what the NF-A series 140mm model can do when it's released.
 

Darkbreeze

Titan
Moderator
You will have crap performance if you put a 120mm fan on a heatsink meant for a 140mm fan. You will get so much reversion leakage that you will likely lose ~30% of your focused airflow.

Yes, the NF-A12x25 fans are very good, but not for a 140mm application. Now, for any location on that heatsink where a 120mm fan is used, then it would make a good upgrade.

The NF-A12x25 PWM has about 63% higher static pressure than the NF-P12 and about 10% higher free air CFM, BUT, under the conditions of a high resistance mount on a heatsink the higher static pressure will actually dramatically increase the ability of the fan to actually sustain that level of airflow through the restrictions whereas with a lower static pressure fan a good deal of it will be lost to leakage and reversion.

If you REALLY want to see a significant bump in performance, and are not terribly concerned with a little more noise, this will give you better performance than anything you can do with the NH-D15.

 
Jan 9, 2020
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Thank you for your comments Darkbreeze, much appreciated. The size of the D14 is almost exactly the size of a 120mm fan, which is why I thought it could possibly do really well on it, and also that 1 out of 2 fans on it were originally 120mm anyway.
I bought one A12x25 PWM for a case exhaust fan, and was thinking of getting another one for intake, so I guess the only sensible thing to do is to do a proper comparison between the three setups (D14 with original fans, D14 with A15's and D14 with A12x25's), run some tests and see what the temp differences are.

Edit: I meant to say that I had seen that article on Overclockers all right, I read that before I bought the 2 x A15's, I was sold on the low noise and still decent performance of them compared to the original fans.

Currently I'm using the old fans from the D14 on my GPU:

https://forums.tomshardware.com/threads/140mm-120mm-fans-for-gpu-w-twin-turbo-ii-2-x-noctua-nf-a15-for-nh-d14.3563315/
 
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Darkbreeze

Titan
Moderator
Yes, but in regards to the D14, the Noctua NF-A14 2000rpm fans have 176% more static pressure and 58% higher CFM than the NF-A15 fans do. The static pressure, when used on a heatsink or radiator, will usually be the telling factor when other specifications (normally tested under free air conditions, not with a major restriction) are otherwise equal.

120mm fans are NORMALLY often found to have higher static pressures than similar spec'd 140mm fans, but in this case the iPPC fans are far beyond what the A12x25 offers.

I have the A14 2000rpm iPPC fans on my NH-U14S and the maximum PWM overclocked temperature in Prime95 testing dropped by 8°C with two of them on the heatsink versus only one NF-A15 that it came with. That's a significant decrease in thermals.

Considering it is only a slim style single finstack heatsink, you can assume the difference might be higher on the twin finstack D14 or D15, or any much larger heatsink. But I think the A12x25 fans are pretty terrific as well and will absolutely be a quieter option.
 
Jan 9, 2020
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So far I bought one for a 120mm slot at the back of the case for exhaust. Yes, it moves a LOT of air for the noise emitted. Love it. Would love to replace the two intake fans as well, but another 60 buckaroos is a lot. I'm a sucker for low noise, so for my own PC, I wouldn't go for any of Noctua's industrial fans, in any situation.
 

Darkbreeze

Titan
Moderator
Their industrial fans don't make any appreciably higher noise than the standard version of the same fan UNTIL you allow them to go beyond about 1700rpm. I can vouch for that fact because I've run them on my bench in an open air "to my ears" comparison AND I run them in my case.

Being as you can cap the maximum RPM in practically all BIOS fan profile settings these days, it is only if you are running much older hardware with a BIOS that is severely limited in the depth of options that you might have an issue there.

I think that any fan location that allows for the installation of both 120mm and 140mm fans is better off with a 140mm fan, depending on the capabilities of that fan, than it is with even a very good 120mm fan so long as the 140mm model has halfway decent static pressure capabilities because the physical fact of the larger footprint tends to cut down on the potential for reversion airflow or leakage especially if there is moderate resistance to airflow due to the grill pattern design or if it is a heatsink or radiator.

But definitely those fans you are looking at are a very good choice when compared to any other 120mm on the market, even those from Noctua.
 
Jan 9, 2020
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Yeah that's a good point about limiting the top end rpm, didn't think of that. Not sure if my aging Asus Z97-A USB 3.1 mobo supports that, looking at it briefly I could only find "Silent", "Standard" and "Turbo" fan modes for each fan. I could probably use Speedfan etc, but I don't fancy too many memory-resident apps running in the background, already have too many of those, these days one "needs" separate apps for keyboards, mice, wheel, flight stick etc. :)
 

Darkbreeze

Titan
Moderator
I don't like speedfan.

Generally speaking, any BIOS that allows you to create a custom fan curve can do this, and those that don't, cannot.

I prefer to not have a bunch of unnecessary utilities installed either. I'm much rather see it all happen from the BIOS since it has to be there anyhow.
 

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