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TESTING
For a fuller understanding of ATX power supplies, please read the reference
article Power Supply Fundamentals & Recommended
Units. Those who seek source materials can find Intel's various PSU
design guides at Form
Factors.
For a complete rundown of testing equipment and procedures, please refer to
SPCR's PSU Test Platform
V.3. The testing system is a close simulation of a moderate airflow
mid-tower PC optimized for low noise.
In the test rig, the ambient temperature of the PSU varies proportionately
with its output load, which is exactly the way it is in a real PC environment.
But there is the added benefit of a high power load tester which allows incremental
load testing all the way to full power for any non-industrial PC power supply.
Both fan noise and voltage are measured at various standard loads. It is, in
general, a very demanding test, as the operating ambient temperature of the
PSU often reaches >40°C at full power. This is impossible to achieve
with an open test bench setup.
Great effort has been made to devise as realistic an operating
environment for the PSU as possible, but the thermal and noise results obtained
here still cannot be considered absolute. There are too many variables in PCs
and too many possible combinations of components for any single test environment
to provide infallible results. And there is always the bugaboo of sample variance.
These results are akin to a resume, a few detailed photographs, and some short
sound bites of someone you've never met. You'll probably get a pretty good overall
representation, but it is not quite the same as an extended meeting in person.
REAL SYSTEM POWER NEEDS: While our testing loads the PSU to full output
(even >600W!) in order to verify the manufacturer's claims, real desktop
PCs simply do not require anywhere near this level of power. The most pertinent
range of DC output power is between about 65W and 250W, because it is the power
range where most systems will be working most of the time. To illustrate this
point, we conducted system tests
to measure the maximum power draw that an actual system can draw
under worst-case conditions. Our most power-hungry Intel 670 (P4-3.8) processor
rig with nVidia 6800GT video card drew ~214W DC from the power supply under
full load — well within the capabilities of any modern power supply. Please
follow the link provided above to see the details. It is true that very elaborate
systems with the most power hungry video card today could draw as much as another 60~100W, but the total
still remains well under 400W in extrapolations of our real world measurements. As for high end dual video card gaming rigs... well, to be realistic, they have no place in silent computing today.
SPCR's high fidelity sound
recording system was used to create MP3 sound files of this PSU. As
with the setup for recording fans, the position of the mic was 3" from the exhaust
vent at a 45° angle, outside the airflow turbulence area. The photo below shows
the setup (a different PSU is being recorded). All other noise sources in the
room were turned off while making the sound recordings.
INTERPRETING TEMPERATURE DATA
It important to keep in mind that fan speed varies with temperature,
not output load. A power supply generates more heat as output increases, but
is not the only the only factor that affects fan speed. Ambient temperature
and case airflow have almost as much effect. Our test rig represents a challenging
thermal situation for a power supply: A large portion of the heat generated
inside the case must be exhausted through the power supply, which causes a corresponding
increase in fan speed.
When examining thermal data, the most important indicator of cooling efficiency
is the difference between intake and exhaust. Because the heat
generated in the PSU loader by the output of the PSU is always the same for
a given power level, the intake temperature should be roughly the same between
different tests. The only external variable is the ambient room temperature.
The temperature of the exhaust air from the PSU is affected by several factors:
- Intake temperature (determined by ambient temperature and power output level)
- Efficiency of the PSU (how much heat it generates while producing the required
output)
- The effectiveness of the PSU's cooling system, which is comprised of:
- Overall mechanical and airflow design
- Size, shape and overall surface area of heatsinks
- Fan(s) and fan speed control circuit
The thermal rise in the power supply is really the only indicator
we have about all of the above. This is why the intake temperature is important:
It represents the ambient temperature around the power supply itself. Subtracting
the intake temperature from the exhaust temperature gives a reasonable gauge
of the effectiveness of the power supply's cooling system. This is the only
temperature number that is comparable between different reviews, as it is unaffected
by the ambient temperature.
240V AC TEST SETUP
As mentioned earlier, some work had to be done to get 240V AC into the lab, along with test instrumentation that would give us AC data. The Kill-a-Watt and Seasonic Power Angel AC power meters work only on 120V AC with US/Canada AC jacks.
The room where the PSUs are tested used to be a spare kitchen. In fact, there is a 120/240V three phase AC outlet for an electric stove/oven directly behind the cabinet on which the PSU test loader rests. This dedicated outlet runs directly off two 15A/120V circuit breakers in the main electrical panel. This feature makes it ideal for use as a dedicated PSU test AC line. (Especially now that we have a 1,000W PSU awaiting testing in the wings: It will probably trip a 15A breaker if we try to get full output.) We obtained a power cord for use with this outlet, then ran the leads to two paired utility AC outlets, one pair for 240VAC and the other pair for 120VAC.
 
The dedicated heavy-duty 240VAC appliance
outlet and plug. The standard Canada/US 120VAC plug is dwarfed in comparison.
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The dedicated 240VAC and 120VAC outlets are only for PSU testing. The Extech 380803 Power Analyzer / Data logger in the background has no trouble with 240VAC, which is run through the unit. The LED display shows that 244VAC is at the input.
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FINALLY, THE TEST RESULTS
Ambient conditions during testing were 21°C and 18 dBA. AC input was 244V, 60Hz.
|
OUTPUT & EFFICIENCY: Be Quiet! Dark Power Pro 430
|
|
DC Output Voltage (V) + Current (A)
|
Total DC Output
|
AC Input
|
Calculated Efficiency
|
|
+12V1
|
+12V2
|
+5V
|
+3.3V
|
-12V
|
+5VSB
|
|
12.03
|
0.94
|
12.02
|
1.70
|
5.10
|
0.95
|
3.38
|
0.95
|
0.1
|
0.2
|
42.0
|
62
|
67.7%
|
|
12.02
|
1.87
|
12.01
|
1.68
|
5.10
|
1.89
|
3.38
|
2.76
|
0.1
|
0.4
|
64.8
|
85
|
76.3%
|
|
12.01
|
1.84
|
12.01
|
3.19
|
5.10
|
2.77
|
3.38
|
3.62
|
0.2
|
0.5
|
91.7
|
119
|
77.0%
|
|
12.01
|
3.76
|
12.00
|
4.95
|
5.10
|
4.77
|
3.38
|
4.74
|
0.3
|
0.8
|
152.5
|
194
|
78.6%
|
|
12.00
|
5.60
|
12.00
|
6.60
|
5.10
|
5.65
|
3.35
|
4.65
|
0.4
|
1.2
|
201.6
|
248
|
81.3%
|
|
12.00
|
7.70
|
11.96
|
6.60
|
5.07
|
8.23
|
3.35
|
7.80
|
0.5
|
1.5
|
252.7
|
314
|
80.5%
|
|
11.95
|
8.60
|
11.96
|
9.64
|
5.08
|
8.23
|
3.37
|
7.80
|
0.6
|
1.8
|
302.4
|
374
|
80.8%
|
|
11.88
|
13.10
|
11.88
|
12.60
|
5.02
|
13.20
|
3.34
|
11.00
|
0.8
|
2.5
|
430.4
|
557
|
77.3%
|
|
NOTE: The current and voltage for -12V and +5VSB
lines is not measured but based on switch settings of the DBS-2100 PS
Loader. It is a tiny portion of the total, and potential errors arising
from inaccuracies on these lines is <1W.
|
|
OTHER DATA SUMMARY: Be Quiet! Dark Power Pro 430
|
|
DC Output (W)
|
42.1
|
64.8
|
91.7
|
152.5
|
201.6
|
252.7
|
302.4
|
430.4
|
|
Intake Temp (°C)
|
23
|
25
|
28
|
31
|
34
|
38
|
40
|
47
|
|
Exhaust Temp (°C)
|
25
|
26
|
30
|
34
|
38
|
45
|
46
|
55
|
|
Temp Rise (°C)
|
2
|
1
|
2
|
3
|
4
|
7
|
6
|
8
|
| Fan Voltage (V) |
4.3
|
4.3
|
4.6
|
5.3
|
6.3
|
7.0
|
7.8
|
9.7
|
| SPL (dBA@1m) |
21
|
21
|
22
|
24
|
26~27
|
30
|
32
|
35
|
|
Power Factor
|
0.85
|
0.90
|
0.97
|
0.98
|
0.98
|
0.98
|
0.98
|
0.98
|
AC Power in Standby: 0.9W / 0.04 PF
AC Power with No Load, PSU power On: 14.4W / 0.45 PF
|
|
NOTE: The ambient room temperature during testing
can vary a few degrees from review to review. Please take this into account
when comparing PSU test data.
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ANALYSIS
1. LOW LOAD PERFORMANCE
Power consumption in standby mode was quite low, coming in at ~0.9W. Power factor was 0.04, which is difficult to understand. The power supply started properly
with no load applied on the test bench, drawing a moderately high 14.4W at 0.45 PF. This suggests that the unit has built-in additional resistance to ensure low-current startup. Whether that additional load is dynamic is not clear, but the efficiency at higher loads is fairly good, so we suspect it is some kind of dynamic minimal loading.
2. VOLTAGE REGULATION was tops; none of the voltages fluctuated
by more than +2.4% and -1.0%. Mostly they were dead on.
3. EFFICIENCY was very good compared to most PSUs we've tested, and about average for a recent ATX12V v2.2 power supply. The peak
of 81.3% was reached at 200W and stayed above 80% until close to maximum output where it dipped a bit. At lower loads,
efficiency was moderate, but reached 76.3% at 65W. Most
systems require little more power than this at idle and tend to spend much of their time idling. This PSU would be fairly efficient under real world circumstances.
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EFFICIENCY ADVANTAGE AT 240V AC
Because this unit is the first to be tested at 240VAC input, we wondered how much of an efficiency advantage it had compared to all the others we've tested with 120VAC input. To get some idea of the answer, we grabbed the nearest "free range input" power supply and tested it at a few selected power points, first at 120VAC, and then at 240VAC. The results on this early Antec NeoHE 430 are tabulated below.
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Antec NeoHE 430 Efficiency at 120VAC and 240VAC
|
|
DC Output
|
120VAC
input
|
240VAC
input
|
Δ
|
|
Power
|
Efficiency
|
Power
|
Efficiency
|
|
66W
|
90W
|
73.3%
|
88W
|
75.0%
|
+1.7%
|
|
153W
|
189W
|
80.1%
|
183W
|
83.6%
|
+3.5%
|
|
253W
|
317W
|
79.8%
|
305W
|
83.0%
|
+3.2%
|
|
430W
|
574W
|
74.9%
|
545W
|
78.9%
|
+4.0%
|
The difference in power efficiency was smallest at low power and highest and high power. It ranged, for this sample, from a minimum of 2W or 1.7% at 66W output to a maximum of 29W or 4% at 430W output.
If this 2~4% efficiency advantage at 240VAC can be said to be typical, then the Be Quiet! test sample would have to be considered somewhat below average in efficiency for a high end PSU.
However, a 120/240 VAC comparison of efficiency on a single sample is hardly conclusive. We did try a few other full range AC input PSUs from Seasonic, Enhance and Enermax, and found very similar 2~4% differences. A more formal presentation of this issue and the corresponding test data will be presented in our next PSU test rig update, which will probably come in the next month or two.
|
4. POWER FACTOR was excellent thanks to the active power factor correction
circuit, staying very
close to the theoretical maximum of 1.0.
5. TEMPERATURE & COOLING
Cooling in the Be Quiet! was not a cause for concern. The temperature
differential between in/out never rose above 8°C — a very good result. The temperature
stayed modest in absolute terms. The 55°C exhaust temperature reached
at the end of the test suggests good cooling.
As with many low speed fan PSUs, the Dark Power Pro should be considered only as a minor player in system cooling. Its fan is designed mostly to keep itself cool, not to provide ancillary cooling for other components in the system.
6. FAN, FAN CONTROLLER and NOISE
The quality of noise at turn-on was very good: Quiet, smooth and devoid of tonal or cyclical annoyances. The baseline SPL was about as low as we've recorded for any fan-cooled PSU at 21 dBA@1m.
The early promise continued as the load on the PSU was increased. The control circuit exhibited a smooth, slow-rising increase in fan speed/noise that puts it in a select group of the quietest PSUs. The 26~27 dBA reached at 200W output is not quite the equal of the most recent Seasonic S12 Energy Plus and M12 models (which remained at 21 dBA@1m even >250W), but it's roughly on par with earlier S12s and the Antec NeoHE, both of which are still extremely quiet. There's little question that this Be Quiet! DP Pro 430 is an impressively quiet power supply. It's too bad distribution is limited to 240VAC locales.
|
Power Supply SPL (in dBA@1m) Vs. Power Output
|
|
Model
|
65W
|
90W
|
150W
|
200W
|
250W
|
300W
|
400W
|
| Be Quiet! DP Pro 430 |
21
|
22
|
24
|
26~27
|
30
|
32
|
35
|
|
Antec NeoHE 430
|
20
|
20
|
21
|
26
|
31
|
37
|
40
|
|
Seasonic S12-430
|
20
|
20
|
22
|
25
|
29
|
32
|
37
|
|
Seasonic S12 Energy Plus 550/650
|
20
|
20
|
20
|
20
|
21
|
25
|
38
|
|
Silverstone Element Plus ST50EF-Plus
|
23
|
23
|
23
|
25
|
34
|
41
|
43
|
|
Zalman ZM460-APS
|
22
|
23
|
26
|
29
|
31
|
34
|
37
|
|
Enermax Liberty EL500AWT/EL620AWT
|
21
|
21
|
24
|
30
|
35
|
38
|
41
|
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