Noctua NH-D14 flagship dual-fan CPU cooler

Cooling
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COOLING TEST RESULTS

How likely is the average user going to replace the fans on his new $90~100 CPU heatsink? That's a relevant question for this review. "Not likely" seems to be the most likely answer, considering that the stock fans are quieter than average, and the replacement fans could cost as much as $40 in total.

In that case, at what voltage should the stock fans be set for testing? Keep in mind that we consider it important to be able to make apples-to-apples comparisons with other heatsinks we test. Normally, the same reference fan is used at specific voltages (12, 9, 7, and 5V). This question required some careful thought.

In the end, experimentation with the supplied noise/speed reducing adapters provided the answer.

  1. Naturally, a test at full fan voltage/speed is needed: 12V.
  2. When the blue adapter is used on the 12cm fan, the black adapter on the 14cm fan, and the two fans run together (as per the instructions), the resulting 21 dBA@1m SPL is about same as when a straight ~8.5V is applied to both fans. Since this would be a common user option, 8.5V looked like a good choice.
  3. If the 14cm fan is run by itself, using the black adapter results in 8.5V to the fan, and the blue adapter provides 7.3V. We had a third fan voltage point. (The adapters give slightly higher voltages for the 12cm fan, 8.8V and 7.7V, but to keep the data from overwhelming us, 8.5V and 7.3V were used with both fans.)
  4. Since 6.5V is the minimum reliable start voltage for the 14cm fan, this is a natural test point. Users will find a way to get this voltage/speed if they want to.
  5. The 12cm fan starts at 4.8V, so the usual 5V test point seems a natural, as it is easy to obtain in a computer.

The SPL values of these various fan settings intersect closely enough with the SPL obtained from the reference fan or with the stock fans of other fans. Still, it was decided in the end, to run tests with the reference fan as well. Many potential buyers of the NH-D14, at least among regular SPCR visitors, will probably already have a collection of various quiet fans that they may experiment with. (Most readers know that the Nexus 120 is a rebranded, very slow speed, sleeve bearing Yate Loon, which is modestly priced just about everywhere.)

There were 10 test runs, with data collected at 4-5 voltage/speed points for each run. Some runs were repeated because the results did not seem credible. The time required for these thermal tests and to measure/record all the sonic permutations extended many, many days.

  1. With CPU at default settings: A test run with both stock fans, one fan, then the other fan.
  2. With CPU overclocked/volted: Repeat of the above three sets.
  3. With CPU at default settings: A test run with one reference Nexus 12cm fan, then two.
  4. With CPU overclocked/volted: Repeat of the the two sets in #3.

When only one fan was used, it was always placed in the center between the two fin stacks.


Noctua 12cm fan nearly invisble in center.

TEST SET A: Stock fans, default CPU settings

The cooling results with the stock dual-fan configuration are excellent. At every matching SPL, the stock dual-fan equipped Noctua NH-D14 cools at least a degree or two (and often, many degrees) better than the closest competitor equipped with a single fan. As expected with dual push-pull fans, the cooling performance drops off very little when the fans are undervolted. The difference between 12V and 6.5V is just 3°C; with either of the fans by itself, the drops is 6°C or 8°C.

Noctua NH-D14 w/ Stock Fans, i7-965 default settings
Fan Voltage
NF-P14 only
Both fans
NF-P12 only
SPL
°C Rise
SPL
°C Rise
SPL
°C Rise
12V
30
32
30
31
24
36
8.5V
20
34
21
33
17
39
7.3V
16
35
17
33
14
41
6.5V
14
38
14.5
34
12
44
5V†
-
-
12
38
11
51
*See above text for explanation of chosen fan voltage points
°C Rise is the rise above the temperature of the intake air.
Note that the 5V reading for 2 fans can only be achieved by reducing the voltage after the 14cm fan is already spinning at a higher speed.

Comparing the dual-fan NH-D14 is a bit difficult because we have not yet tested any other heatsinks with two fans on the i7 test platform. The only comparative data set consists of the eight HS tested with a single Nexus 120 fan in our i7 platform introduction article, which gives at least a starting point.

°C rise Comparison: i7-965 default settings
Heatsink
Nexus 120mm fan voltage /
SPL @1m
Rank
12V
9V
7V
16 dBA
13 dBA
12 dBA
Prolimatech Megahalems
35
39
42
#2
Scythe Mugen-2
37
40
43
#3
Noctua NH-U12P
38
40
41
#3
Thermalright Ultra-120 eXtreme
38
41
45
#4
Zalman CNPS10X
Extreme
39
43
48
#6
Thermalright Ultra-120
42
44
49
#7
Scythe Kabuto
43
48
54
#8
Noctua NH-C12P
44
47
54
#8
Noctua NH-D14 - dual stock Fans
17 dBA
14.5 dBA
38
#1
33
34
Noctua NH-D14 - 14cm fan only
16 dBA
14 dBA
n/a
#2
35
38
Noctua NH-D14 - 12cm fan only
17 dBA
14 dBA
44
#5
39
41

The closest match for the 16 dBA SPL of the reference Nexus 120 at 12V is the two Noctua fans at 7.3V: 17 dBA. The 33°C rise achieved by the Noctua NH-D14 at this setting bests the Prolimatech Megahalems by two degrees. But since there is a 1 dBA advantage for the NH-D14, perhaps the difference should be considered to be only 1°C. At the lower speed/noise levels, the dual-fan Noctua's thermal advantage grows: 4°C over the Megahalems and 3°C over smaller brethren NH-U12P at 12 dBA.

With the single 14cm fan, the NH-D14 matches the Megahalems at 2nd place, which suggests that this is the fan that's really doing much of the cooling. When only the 12cm fan is used, its performance drops substantially, and its ranking in the table above falls to 5th place.



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