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PRELIMINARY RESULTS
To verify that the new airflow test box
could produce useful results, we tested a handful of fans that have already been measured the previous way. The results are summarized in the table below. You'll notice the airflow is reported in LFM (Linear Feet per Minute) instead of the usual CFM (Cubic Feet per Minute) unit we've used in the past. The reason for this will come later.
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Airflow Measurements Compared: LFM of 120mm Fans
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|
Fan
|
Method
|
12V
|
9V
|
7V
|
5V
|
|
Arctic Fan 12L
|
old
|
350
|
270
|
200
|
120
|
|
new
|
390
|
300
|
230
|
140
|
|
Antec TriCool
|
old
|
770
|
610
|
470
|
320
|
|
new
|
810
|
650
|
530
|
370
|
|
Nexus 120
|
old
|
480
|
360
|
270
|
160
|
|
new
|
470
|
370
|
300
|
210
|
|
Noctua NS-S12-1200
|
old
|
650
|
530
|
430
|
310
|
|
new
|
590
|
480
|
390
|
280
|
|
Scythe S-Flex SFF21E
|
old
|
550
|
390
|
280
|
140
|
|
new
|
600
|
430
|
310
|
170
|
|
SilenX IXP-74-11
|
old
|
580
|
470
|
420
|
330
|
|
new
|
510
|
420
|
360
|
270
|
The exceptional fans, the ones that produced suspect measurements
before, now produced results more in line
with our expectations. The results for the Noctua and SilenX fans — both
of which previously measured unaccountably high — dropped down closer to
what we would expect. And the results for the reverse-direction Arctic Fan
12L rose slightly, though it still seemed to blow less air at a given speed than
the more conventional fans we tested. The Antec Tricool and Scythe fans also measured higher. The Nexus measurements were closest to each other, but the new method showed greater airflow at low speed.
The graphs of the data may be easier to understand. The two sets of measurements for each fan is in similar colors to make them easier to see and to compare. Note how most of them run parallel to each other.
All in all we were quite pleased with the result. This airflow measurement method
seemed to produce more reliable results, and it also simplified testing. We could now dial in a specific voltage
with any fan, and quickly obtain an airflow measurement consistent within 10~20
LFM. Quick, consistent results were very difficult to obtain with our old manual technique.
We also tested a few 92mm and 80mm fans to see how they were affected.
Here, we found bigger differences between the old measurements and the new ones. The measured airflow of virtually every fan we tested dropped substantially.
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Airflow Measurements Compared: LFM of 80mm & 92mm Fans
|
|
Fan
|
Method
|
12V
|
9V
|
7V
|
5V
|
|
Nexus 92
|
old
|
490
|
390
|
300
|
190
|
|
new
|
410
|
320
|
250
|
150
|
|
Fander FX92-W
|
old
|
810
|
640
|
480
|
340
|
|
new
|
580
|
460
|
360
|
250
|
|
Nexus 80
|
old
|
550
|
370
|
250
|
120
|
|
new
|
390
|
280
|
180
|
100
|
|
Scythe SA0825FDB12SL
|
old
|
630
|
440
|
300
|
140
|
|
new
|
420
|
310
|
200
|
100
|
|
Arctic Fan 3
|
old
|
320
|
260
|
170
|
90
|
|
new
|
410
|
320
|
260
|
160
|
The graph below illustrates it more dramatically. This time, the pair of curves for each fan is the same color. Note how much wider the gap is between the two lines for most of the fans, compared to the 120mm fans above. The greater difference at 12V is more marked as well.
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