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TEST RESULTS
- For a fuller understanding of ATX power supplies, please read our article Power Supply Fundamentals & Recommended Units.
- Those who seek source materials can find Intel's various PSU design guides, closely followed by PSU manufacturers, at Form Factors.
- For a complete rundown of testing equipment and procedures, please refer to the
article
SPCR's Revised PSU Testing System. It 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 actual output load, which is exactly the way it is in a real PC
environment. But there is the added benefit of a precise 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 loads. It is, in general, a very demanding test, as the operating
ambient temperature of the PSU often reaches 40°C or more 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 far to many variables in PCs and far 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 reasonably good overall impression of that person, but it is not quite the same as an extended meeting in person.
REAL SYSTEM POWER NEEDS: One very important point is that the 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
recently conducted system tests to measure the maximum power draw that an actual
system can draw under worst-case conditions. Our most powerful P4-3.2
Gaming rig drew ~180W 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 150W, but the total still remains well under 400W in
extrapolations of our real world measurements.
The Raidmax casts that eerie blue glow that is so fashionable right now.
Ambient conditions during testing were 20°C and 20 dBA, with input of 120 VAC
/ 60 Hz measured at the AC outlet.
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Raidmax RX-520XPW TEST RESULTS
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DC Output (W)
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65
|
90
|
150
|
200
|
250
|
300
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465*
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AC Input (W)
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86
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117
|
196
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255
|
322
|
385
|
640
|
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Efficiency
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76%
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77%
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77%
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78%
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78%
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78%
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73%
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Intake Temp (°C)
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23
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26
|
30
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32
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35
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39
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41
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PSU Exhaust (°C)
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30
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35
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42
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47
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51
|
54
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65
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Fan Voltage
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5.7
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5.7
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5.9
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7.4
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9.5
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10.3
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11.1
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Noise (dBA/1m)
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22
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22
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24
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30
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35
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37
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45
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Power Factor
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0.62
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0.63
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0.65
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0.66
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0.67
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0.67
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0.68
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NOTE: The ambient room temperature during testing
varies a few degrees from review to review. Please take this into account
when comparing PSU test data.
* Test stopped in <5 minutes due to high temperature.
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ANALYSIS
1. VOLTAGE REGULATION was excellent, within ±3% on all lines
for all tested loads. Fluctuations in voltage are mainly caused by changes in
load and unbalanced loads, so greater fluctuation may be observed in a real
system.
-
+12V: 12.2 to 12.3
-
+5V: 4.9 to 5.1
-
+3.3V: 3.2 to 3.3
2. EFFICIENCY was average. Performance in the mid-to-high seventies
is far from terrible; however, it is not up to modern standards. Many of the
power supplies that we have tested in recent months have peaked above 80%.
3. POWER FACTOR: There did not appear to be any power factor correction
implemented in the Raidmax. Power factor began at 0.62 and increased to 0.68
at full load.
4. TEMPERATURE: Ordinarily, we do not consider the internal temperature
very relevant to our evaluation of a power supply. Efficiency is
a much better indicator of exactly how much heat is being produced inside the
unit because that measurement is more precise, not dependent on a single thermal sensor.
Still, in most of the power supplies we've reviewed, the rise in temperature between intake
and exhaust is around 5°C under typical load, increasing to roughly 10°C
at full tilt. A well cooled power supply can manage lower than this. By comparison,
the Raidmax has a rise of 9-15°C under a normal load, and well over 20°C
fully loaded. In fact, we stopped our full load test after ~5 minutes
because the exhaust temperature appeared to be increasing without bound. The
documentation for the Raidmax does not list over-temperature protection as a
feature.
5. FAN, FAN CONTROLLER and NOISE: The test environment is live, so readings are higher than would be obtained in an anechoic chamber readings.
Despite our apprehension regarding the clear plastic construction of the fans,
the Raidmax was quite well behaved sonically. The starting voltage from the
fan controller was 5.7V at our baseline 65W load. Subjectively, the fans at this
level sounded fairly smooth and motor noise was minimal. Inside a case this noise
would probably fall below ambient levels in most environments.
Raidmax seemed to have the right idea with the fan controller. The fan voltage
increased very little until ~200W output was reached. See the temperature section
above for the effect this had on temperatures. Changes in fan voltage were gradual
and no audible shifts in fan speed were noticed.
As with many other power supplies, the point that the Raidmax became intrusive
acoustically was around 200W output. The noise was an even motor hum; little buzzing
or clicking was evident. The characteristic buzzing of clear plastic did not
seem to be an issue.
Above 200W, the Raidmax quickly moves from being somewhat quiet to decidedly
noisy. We would not consider the Raidmax a wise choice in a system that draws
more than 200W. Additionally, an irritating high frequency coil whine developed
after a about minute at full load. This whine disappeared almost immediately
when we reduced the load.
After the power supply was shut down, the fans continuted to spin at 3.9V for
a few minutes to exhaust the remaining heat from the case. At this voltage level
the fan noise fell below the ambient noise level in our lab, rendering them
unmeasurable.
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