There are many technical ways to test fans and come up with a bunch of numbers to show that one fan is better than another. The other way, the more organic approach, is to simply install it, listen to it, and see how well they cool!
With our test rig stuffed to the brim with Noctua fans and the XSPC Raystorm 750 RS240 kit still installed I switched her on and braced for a thunderous sound to come tearing from the case. To my surprise, it was very reasonably quiet. The only fans not Noctua in the rig were the XSPC ones set to pull on the radiator. These were set up on a separate controller and turned up they easily muted out the Noctua’s. Turning them off, and with all Noctua fans set to full power I could certainly hear them, but for 5 fans blasting away it created a gentle whooshing sound. Reducing the power to them only further decreased the noise level, to a point where they were barely audible. I paid especially close attention to the sound while switching speeds. And they were all amazing consistent and smooth.
Since I had recently tested the XSPC kit I re-checked some numbers with all the Noctua fans in the case. The test case is now doing a push pull on the RS240 radiator, there are two 140mm fans exhausting from the top, and one 120mm fan exhausting from the rear.
The ambient testing temperature was up slightly to 72F (The XSPC kit was tested at 68F) on this day. The result was an average stock clocked CPU idle core temperature of 31.75C/89.15F. This was dead even with the radiator in pull only and stock case fan of the XSPC review.
The first screenshot is from the XSPC review, the second with the Noctua fans. And in spite of 4 degree temperature rise the Noctua fans kept things even.
Next I ran IBT at the maximum memory setting for a single pass to see what that would do.
The result was a core average for the stock clocked CPU of 45C/113F. The XSPC kit alone ran at an average of 43C/109.4F.
This result puts them about even once adjusted temperature gain.
So far we have tested these Noctua fans:
However we still have four more fans from Noctua. Unfortunately I do not have anything to test them in for their intended purposes. Instead I hooked them individually to my Lamptron FC-5V2 fan controller and ran them. I checked their top speed at highest voltage as well as lowest speed at the lowest voltage they will operate at all while listening for consistency, pitch and overall noise.
Noise: Very quiet. At max speed a little whiney but moves quite a bit of air.
Typical Use: Motherboard heatsinks, Server cooling
Noise: Mostly totally silent up until top speed. Noise at top speed more of a whooshing sound. Moves a surprisingly large amount of air!
Typical Use: HTPC’s/Smaller cases, Low power processors
NF-A9x14 PWM 92x14mm:
Noise: This fan is an ultra low profile design and as such it has to give things up. For one it was not a very pleasant sounding fan at speed. And even at full speed it did not move a very large amount of air for the noise it makes. Space saving is going to be this fans specialty.
Typical Use: Any where a thicker 25mm fan is too wide. Heatsink, HTPC case, etc.
NF-A15 PWN 150x25mm:
Noise: I would say exactly as expected. At lower speeds it’s not there. At high speed it’s a consistently smooth whoosh that is almost pleasant. This fan moves a great deal of air for not a lot of noise.
Typical Use:High end air coolers. Dimensionally tailor-made to fit more cases and heatsinks. This fan has 120mm hole spacing so it will even fit on 120mm CPU coolers if you have room.