I don’t know, but the tests were for the PQ curves so it must be variable resistance. The reports do have the test equipment model listed. I’m sure one can find out the exact methodology.
Yep, sorry for the confusion brought on by me not linking the sources and elaborating on things.
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For the 140mm fan I sourced it from a page that includes the P/Q curve that included both the r and non r variants https://www.noctua.at/en/expertise/tech/nf-a14x25-g2-performance-improvements titled " NF-A14x25(r) G2 performance: improvements for heatsinks, radiators and cases"
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For the 120mm variant I sourced it from a page that includes the P/Q curves that includes both G1 and G2 on the graph https://www.noctua.at/en/expertise/tech/nf-a12x25-g2-performance-improvements titled “NF-A12x25 G2: further refined performance in all applications”. What I SHOULD have included was the annotation I had in my head from that Noctua page you’re referring to that states the higher peak the stock Framework provided fan can hit, noting that it is the G1 variant. But as the “blue line” of the regular speed A12x25 G1 is much lower than the “green line” in the graph, I was assuming it would land somewhere in-between. I should have added and elaborated on my assumption like I did just here.
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But thanks to user sun we no longer need to assume as there are those 3rd party test to provide empirical evidence to how one should perform vs. another.
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To find Noctua’s own published P/Q curves isn’t obvious. One has to Browse all fans, click the fan page desired, click on a fan in question, click Features, then look for a box that mentions the P/Q nature of that design, which will then provide a link embedded within the text in a not so obvious / subtle way.
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The Noctua published graph is comparing airflow x-axis to pressure y-axis.
- Showing that on a super densely finned radiator, the airflow thru those fins will be decreased more and more as the fins get denser and denser, until you’re left with basically a flat surface. That would give the maximum pressure value at the left side of the graph when airflow is 0.
- And likewise as radiator fins get more an more separated and far apart – our FW mainboard’s fins are quite far apart and length is fairly high so there is a lot of space to flow before air molecules hit and are stopped by the base – until the fins are so far apart that there is no difference in effect on airflow being pushed by the fan. That gives the maximum airflow when the pressure is 0.
- Based on other articles I read on Noctua’s site I surmise the grey line for “Impedance of typical case fan application” is not crossed at a pressure of 0 is because a “typical” case is operating under a positive pressure, having unequal passive airflow or fans operating blowing airflow out of the case compared to entering the case, thus some pressure on the fan blowing into it.
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Great info thanks. I understand the concept, just unclear how it plays out in real life, beyond the basics of as fin gap decreases, static pressure becomes more important, as the gap increases, airflow becomes more important and ambient temperature starts to play an increasingly important role as the temps rise.
I might pickup an nf-a12x25 pwm G2 and do some head to head testing.
My bench style setup will also respond differently to a closed case, as there are no elevated interior case temperature and ventilation issues to consider.
I suspect your bench testing won’t yield anything conclusive G2 versus G1. Not that it is a bad idea to try…but I think we’re missing the forest for the trees here, in terms of the reasoning for recommending a high-static-pressure fan.
TL;DR: It isn’t the heat sink. It is the case.
Flex-ATX class chassis all are scarce on fans, there just isn’t room. And the stock Framework chassis is like most–in that the chassis is positively pressurized via the heatsink fan, which is the only fan. And it not only has to move air through the heatsink–it has to have enough pressure to force air through whatever gaps there are in the case to exhaust it so fresh air can come in. Which is why a fan-funnel is supplied stock, to prevent path-of-least-resistance which would be recirculation. Which is also why people notice warm air coming out of the vented front panel tiles–the fan has enough pressure to force it.
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Well, that’s why I’m using the case I chose to use… hehehe
Thermaltake Core V1 in Snow White. Supplied w/a 200mm fan, but is 3-pin. So I replaced it with the Noctua. Also full 850w ATX PSU I had freed-up from another case installed, runs silent even under load. And I’ve fit 5x 3.5" HDDs inside.
(on it’s back in this pic)
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You just need to add wings and it’ll take off!
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Anyone try the ippc version of the Noctua fan?
Link for reference: https://www.noctua.at/en/products/nf-f12-industrialppc-3000-pwm/specifications
I have two of the 140mm ones I used on a dense fin per inch rad in a case that couldn’t do push-pull, but they did get a little rowdy from time to time… nothing a good fan curve couldn’t solve though.