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TEST RESULTS
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 powerful 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 SLI could draw as much as another 100W, perhaps more, but the total
still remains well under 400W in extrapolations of our real world measurements.
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.
On to the test results...
The Enhance ENP-5136GH on the test bench.
Ambient conditions during testing were 21°C and 19 dBA, Input power was
measured at 122V / 60Hz.
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OUTPUT & EFFICIENCY: Enhance ENP-5136GH
|
|
DC Output Voltage (V) + Current (A)
|
Total DC Output
|
AC Input
|
Calculated Efficiency
|
|
+12V1
|
+12V2
|
+5V
|
+3.3V
|
-12V
|
+5VSB
|
|
12.29
|
0.97
|
12.28
|
1.74
|
5.03
|
0.95
|
3.38
|
0.00
|
0.0
|
0.3
|
39.6
|
54
|
74.0%
|
|
12.30
|
1.91
|
12.29
|
1.74
|
5.03
|
1.91
|
3.35
|
1.85
|
0.1
|
0.5
|
64.4
|
82
|
78.8%
|
|
12.27
|
1.92
|
12.25
|
3.33
|
5.00
|
1.88
|
3.32
|
3.63
|
0.1
|
0.8
|
91.0
|
113
|
80.5%
|
|
12.24
|
2.85
|
12.22
|
12.22
|
4.97
|
4.47
|
3.30
|
7.33
|
0.1
|
1.3
|
150.6
|
187
|
80.7%
|
|
12.22
|
5.64
|
12.20
|
5.03
|
4.94
|
5.33
|
3.27
|
9.56
|
0.2
|
1.7
|
198.7
|
243
|
81.8%
|
|
12.18
|
7.73
|
12.18
|
6.53
|
4.91
|
6.23
|
3.23
|
10.33
|
0.2
|
2.1
|
250.5
|
309
|
81.1%
|
|
12.17
|
8.66
|
12.16
|
8.21
|
4.89
|
7.73
|
3.22
|
12.46
|
0.3
|
2.5
|
299.2
|
374
|
80.0%
|
|
12.17
|
10.48
|
12.15
|
9.73
|
4.87
|
9.26
|
3.24
|
15.94
|
0.3
|
3.0
|
361.1
|
465
|
77.7%
|
|
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: Enhance ENP-5136GH
|
|
DC Output (W)
|
39.6
|
64.4
|
91.0
|
150.6
|
198.7
|
250.5
|
299.2
|
361.1
|
|
Intake Temp (°C)
|
23
|
26
|
31
|
33
|
35
|
36
|
39
|
46
|
|
Exhaust Temp (°C)
|
25
|
28
|
31
|
34
|
37
|
40
|
44
|
52
|
|
Temp Rise (°C)
|
2
|
2
|
0
|
1
|
2
|
4
|
5
|
6
|
| Fan Voltage (V) |
2.8
|
2.9
|
4.4
|
8.6
|
11.2
|
12.1
|
12.1
|
12.1
|
| SPL (dBA@1m) |
<19
|
<19
|
22
|
36
|
40
|
41
|
41
|
41
|
|
Power Factor
|
0.95
|
0.98
|
0.99
|
1.00
|
0.99
|
0.99
|
0.99
|
1.00
|
|
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.
|
ANALYSIS
1. VOLTAGE REGULATION was good, within ±3% throughout the test,
which is good enough to confirm Enhance's claim of ±3% voltage regulation.
2. EFFICIENCY
As expected of an 80 Plus certified power supply, efficiency was very good,
but not quite as good as the other 80 Plus models we've seen. By our testing,
the ENP-5136GH missed 80% efficiency at two of the critical points: 20% and
100% load, corresponding to 72W and 360W output respectively. Extrapolating
between the efficiency measurements between 65W and 90W output, the efficiency
at 72W was 79.3% — just barely shy of the required 80%. This is not enough
of a difference to be significant — the margin of error in our test equipment
is greater.
The drop in efficiency at full load cannot be explained away as measurement
error. A different explanation may apply: Our test bench has very tough thermal
conditions, whereas most industrial testing is done at a constant temperature.
The intake temperature at full load was 46°C, which is a pretty high ambient
working temperature. It's possible the unit could have achieved 80% efficiency
at full load under more favorable thermal conditions.
We did have two samples; the second one was warmed up and tested at full power
output as well. The result was identical (within a few tenths of a percent).
Sample variance or less-than-optimum production QA could account for the lower
than specified efficiency at full output.
3. POWER FACTOR was excellent thanks to the active power factor correction
circuit. Power factor stayed very close to the theoretical maximum of 1.0. It
even got close enough that any difference from the theoretical maximum was not
measurable on our power meter.
4. TEMPERATURE & COOLING
The results of our temperature monitoring system suggested that the cooling
system in the ENP-5136GH is extremely good ? too good to be true. The temperature
rise between intake and exhaust stayed absurdly low until the power supply was
heavily loaded. At one point, there was no difference, which would
suggest that the power supply was producing no heat at all.
Since this was obviously false, we began hunting around for problems with our
measurement setup... and couldn't find any. No matter where we placed the temperature
sensor for the exhaust airflow (the only sensor that moves from test to test),
it never showed a reading above the intake temperature. In several places, it
actually gave a reading below the internal temperature. Eventually,
we gave up and replaced the sensor in its original position.
Our hypothesis about this odd result is that a large portion of the fan airflow
was being exhausted back into the test rig via the large vent on the inside
panel. An informal finger test confirmed that the amount of air being exhausted
through the rear vent was not as high as expected. The intake temperature was
also somewhat higher than it should have been, compared to most previously tested
PSUs at approximately the same 360W load.
No firm conclusions can be drawn about the cooling system, but we are tentatively
optimistic that the unit is capable of cooling itself adequately. It may do
so at the cost of system cooling; some of the waste heat is dumped back into
the system, where it tends to raise the temperature of other components. Users
concerned about system airflow may want to consider sealing up some (not all)
of the vent holes on the inside of the unit. Perhaps a strip of aluminum tape
covering half of each inside vent slot would ensure more of the heat is exhausted
out of the PC.
5. FAN, FAN CONTROLLER and NOISE
As mentioned, the cooling fan in the ENP-5136GH is well known to us. The Seasonic
S12 500W and 600W models both use these fans, and we consider the S12s to be
about the quietest fan-cooled PSUs on the market today. This fan is fairly smooth
for a ball bearing model, and runs quietly at low voltages.
The Enhance confirmed our assessment of this fan. 2.8V may be the lowest starting
voltage we've ever seen. At this level, the noise was below the ambient noise
level in the lab. Even with our ears pressed up against the rear grill, it was
very difficult to hear. Eventually, a flashlight was used to confirm that the
fan was spinning.
The fan voltage stayed at 2.8V at 65W output and increased only slightly at
the 90W target. At this level, it was at roughly the same noise level as the
Seasonic S12. However, the fan speed increased dramatically as soon as a higher
load was dialed in, and the noise level was far from quiet at 150W and above.
This was a bit of a shock; considering the excellent start, we weren't prepared
for the sudden increase in noise.
Compared to the Seasonic S12s, the Enhance was slightly quieter at low loads
(and low ambient temperatures) but much, much louder at higher loads. In a low
heat system with good airflow, the Enhance may be quieter than the S12 in actual
use. However, for higher power systems, the S12 would be a safer choice.
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