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7. FAN, FAN CONTROLLER and NOISE
The fan controller holds the fan speed down until absolutely necessary.
The fan speed didn't budge from its start 330 RPM until the 300W output load
was reached. The noise curve is a flat 11 dBA@1m SPL up to that point, and the
reality is that the actual level could have been even lower, since 11 dBA is
the noise floor of our anechoic chamber.
Quite simply, these PSUs are not audible at under 300W load in
our test rig, not until one's ear is virtually pressed up against the exhaust
grill. The sound was a tiny hum.
Amazingly, even at full load, the SPL was a mere 23 dBA@1m, and
this is with the fan spinning, apparently, at 1000 RPM. Acoustically, at 500W
load, very few other tested PSU come close. The closest is the Nexus NX-5000
at 25 dBA@1m, but its fan starts ramping up at a much lower power level and
is much more audible throughout the middle power range. The Nexus is also much
less energy efficient, with nearly 5% difference at mid power peak.
In a desktop PC without a high power (>100W) graphics card,
regardless of the other components, this PSU is probably never going to be audible.
Exceptions might be if your ambient temperature is hot, say >35°C, or
you try to run with no other fans in your system. If you do run a gaming video
card with >100W peak power, along with some other hefty components like overclocked
125W TDP Phenom or i7 processor and get >300W load, the PSU will become audible
at times... but most likely, it will be drowned out by other fans ramping up
to keep the other components cool enough.
The quality of the noise is moot until the 20 dBA@1m is reached
at the 400W load. Below that, it really was too quiet for sound quality to matter.
At the 20~23 dBA@1m level, there was some buzzing and humming, but these sounds
were audible only from very close up. In normal use, these PSUs are essentially
silent.
11 dBA@1m at up to 250W. Yes, the fan is spinning here, at about
320 RPM according to our calibrated strobe light. There's no real difference
between the ambient (red line) and when the PSU is on.
14 dBA@1m @300W. The fan noise is clearly visible here, mostly
concentrated between 150 and 900 Hz. There's a touch of buzzing centered
around 200 Hz. Above 1,000 Hz, there is nothing.
20 dBA@1m@400W. The 200 Hz buzzing has become more significant.
Most of the noise is between 150 Hz and 2 kHz, although there is some
ultrasonic noise at well over 10 kHz, which can be heard from up very
close as electronic noise.
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One thing we've been examining is how the power supply performs
outside the tough thermal conditions of our standard test. The
recent popularity of cases that isolate the power supply from the rest of the
system make this a relevant question, as the cooler intake air allows the fan
to run slower and quieter. We examine this by rerunning some of the high load
tests with the power supply in free air, away from the tough thermal conditions
of the hot-box.
The results were quite dramatic: Even at full load, the SPL remained
at just 18 dBA. The fan did not speed up until maximum load, and even then it
did not reach full speed. This suggests that in a case with isolated external
intake vent for the PSU, the Enermax 87+ 500W models would remain silent to
just short of full power load.
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Enermax Modu/Pro87+ 500W SPL: In Hot Box vs. Out
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Power load
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90W
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150W
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200W
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250W
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300W
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400W
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500W
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in hot box
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11
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11
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11
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11
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14
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20
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23
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out
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11
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11
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11
|
11
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11
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11
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18
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Measurements are in dBA@1m
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COMPARISONS
The comparison table below shows the SPL versus Power Load data on all the
PSUs tested in the anechoic chamber thus far. It's difficult to rank them, as
the measured SPL varies with power load. The units which are quietest at minimum
load are not always the quietest at midload (100W~300W), which may make them
louder in actual use. Then there's the noise level at 400W and up, which will
determine the quietest PSUs for high power gaming rigs, during actual gaming.
The Enermax Modu/Pro87+ 500W actually manages to be quieter than any other
PSUs at every load, with the sole exception of <100W where
the Seasonic X-650 fanless operation may have a dB or two edge — if indeed
the 11 dBA@1m level is audible to anyone. Up to 250W, it is simply inaudible,
period. The edge over the closest competitors is small, but it's there. At 300W
and above, it becomes somewhat audible but still quieter than all the other
PSUs. The Nexus Value 430 edges it by one dBA at 400W, but it is substantially
noisier from from about 200W on up, so that's a false edge; in actual use, the
Nexus will be more audible more of the time. Overall, other than completely
fanless models, these Enermax Modu/Pro87+ 500W models are the quietest power
supplies we've tested.
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PSU Noise (dBA@1m) vs. Power in Anechoic
Chamber
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Model
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90W
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150W
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200W
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250W
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300W
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400W
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500W
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6-700W
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850W
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Enermax Modu/Pro87+ 500
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11
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11
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11
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11
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14
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20
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23
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n/a
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n/a
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Seasonic X-650
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<10
|
11
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12
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14
|
16
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31
|
31
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32
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n/a
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Nexus Value 430
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11
|
11
|
16
|
18
|
18
|
19
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n/a
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n/a
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n/a
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Nexus NX-5000
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11
|
11
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12
|
14
|
22
|
24
|
25
|
n/a
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n/a
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Antec CP-850
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12
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12
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12
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14
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14
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26
|
40
|
44
|
45
|
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Enermax Eco80+ 500W
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<11
|
12
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16
|
19
|
26
|
32
|
33
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n/a
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n/a
|
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Seasonic M12D 850W
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14
|
14
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14
|
14
|
14
|
24
|
37
|
42
|
42
|
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Enermax Modu82+ 625*
|
13
|
13
|
14
|
15
|
16
|
26
|
36
|
37
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n/a
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Coolermaster M700W
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14
|
14
|
18
|
21
|
25
|
27
|
34
|
34
|
n/a
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Chill Innovation CP-700M
|
15
|
15
|
15
|
15
|
17
|
30
|
34
|
34
|
n/a
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Antec Signature 650
|
15
|
15
|
15
|
18
|
18
|
28
|
36
|
47
|
n/a
|
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SilverStone DA700
|
18
|
18
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18
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18
|
23
|
32
|
35
|
41
|
n/a
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Nexus RX-8500
|
14
|
14
|
17
|
22
|
28
|
32
|
32
|
33
|
33
|
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NesteQ ECS7001
|
22
|
22
|
22
|
21
|
23
|
25
|
36
|
37
|
n/a
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PCPC Silencer 610
|
20
|
24
|
24
|
24
|
24
|
30
|
40
|
50
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n/a
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The green boxes represent >30 dBA@1m SPL.
*Guesstimates based on the Modu82+ 425's idle in the chamber and the Modu82+
625's load test.
Caution: Please keep in mind that the data in the above table is specific to the conditions of our test setup. Change the cooling configuration, the ambient temperature and any number of other factors, and you could change the point at which the fans start speeding up, as well as the rate of the rise in speed. The baseline SPL is accurate, however, probably to within 1 dBA.
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