ePower Lion EP-450P5-L1 Semi-Fanless Power Supply

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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 the article SPCR's PSU Test Platform V.3. 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 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 well over 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 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 40W 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 ¬ó well within the capabilities of any modern power supply. Please follow the link 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 digital 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. 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 PSU 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...

Ambient conditions during testing were 21°C and 19 dBA.

Although the Lion has only a single +12V rail rated at 28A, our test box uses two separate +12V loads, which must be measured independently. The Lion was therefore tested as though it had two 14A rails. Also, we did not test the -5V output because it is no longer used by modern systems.

The thermistor that controls the "Fan Only" voltage was wedged next to the thermistor measuring "Exhaust Temp", so that a correlation between temperature and voltage could be established.

OUTPUT & EFFICIENCY: ePower Lion EP-450P5-L1
DC Output Voltage (V) + Current (A)
Total DC Output
AC Input
Calculated Efficiency
+12V1
+12V2
+5V
+3.3V
-12V
+5VSB
12.05
0.95
12.06
1.71
5.19
1.01
3.33
0.96
0.1
0.2
42.7
59
72.4%
12.17
0.96
12.16
1.73
5.17
3.91
3.34
2.76
0.1
0.4
65.4
86
76.0%
12.13
2.85
12.13
1.72
5.16
4.78
3.34
1.81
0.2
0.5
91.0
116
78.5%
12.16
3.88
12.14
3.29
5.15
7.55
3.34
4.61
0.3
0.8
149.0
187
79.7%
12.15
4.80
12.12
4.97
5.16
10.31
3.35
6.31
0.4
1.1
203.2
258
78.8%
12.16
5.73
12.12
6.46
5.15
12.02
3.33
8.36
0.6
1.4
251.9
325
77.5%
12.17
7.83
12.13
6.47
5.13
15.35
3.29
10.06
0.7
1.7
302.5
399
75.8%
12.16
11.64
12.13
9.64
5.04
23.8
3.24
14.91
1.0
2.5
451.2
640
70.5%

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: ePower Lion EP-450P5-L1
DC Output (W)
42.7
65.4
91.0
149.0
203.2
251.9
302.5
451.2
Intake Temp (°C)
24
25
27
33
35
39
41
44
Exhaust Temp (°C)
30
33
37
47
54
57
60
70
Temp Rise (°C)
6
8
10
14
19
18
19
26
Internal Fan Voltage
0.6
0.6
0.6
1.8
4.7
6.5
8.6
10.9
Fan Header Voltage
5.7
5.7
5.7
5.8
5.8
6.3-6.6
7.6
10.8
SPL (dBA@1m)
*
*
*
*
28
36
39
44
Power Factor
0.59
0.60
0.61
0.64
0.66
0.68
0.69
0.74

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.

*Fan was not spinning at this point, so the measured noise was equal to the ambient noise level.

ANALYSIS

1. VOLTAGE REGULATION

The individual voltage lines varied very little, but all three were a little above their rated values. The +5V rail in particular was as much as 4% high at one point. None of the lines went out of spec, and even at higher power there was little in the way of voltage drop. Indeed, even at the highest output power, the +12V rail stayed steady at approximately 1% above +12V and the +5V rail only dropped marginally. Only the +3.3V rail showed any signs of struggling with the load; it was the only rail that ever dropped below its rated voltage, only at 300W output and above.

2. EFFICIENCY was quite good, peaking just shy of 80% at 150W output. This is a good place for the peak efficiency, since it is close the the maximum of power that most systems are likely to draw. Given its semi-fanless design, efficiency is especially important for the Lion. Efficiency stayed in the upper 70's through most of the output range, falling below 75% only at the highest and lowest loads.

3. POWER FACTOR

The Lion does not have a power factor correction circuit, so power factor was quite poor at lower loads. Power factor improved faster than usual as the power load increased, and reached a high of 0.74 at full load.

4. TEMPERATURE AND COOLING

The thermal performance of the Lion was not good. Below 65W output, the temperature rise stayed below 8°C, but almost doubled to 14°C by the time the output reached 150W. When the fan turned on at around 200W output, the difference between the intake and exhaust temperatures was almost 20°C. When the power supply was going full tilt (and the fan was on full blast), the temperature rise was a scorching 26°C.

This is poor performance, even in comparison to other fanless power supplies. For example, the Antec Phantom 500 only ever saw a rise of 14°C — and this was at the lowest output; the internal cooling improved as the output power increased.

5. FAN, FAN CONTROLLER and NOISE

The Lion actually contains two fan controllers: One which controls the internal fan, turning it on only when absolutely necessary, and one which controls the voltage received by the "Fan Only" cables.

With the fan off, the only noise produced by the Lion is a faint electrical ticking that could not be reliably measured. Suffice to say that it would not be easily heard when it is installed in an actual system.

Internal Fan: For low output loads, the internal fan received less than a volt. The internal fan voltage did not even start to increase until temperature at the external heatsink fins reached 45°C. The fan didn't start spinning until it reached 50°C. In our test setup, this didn't occur until the output reached 200W — above the sustainable output of most midrange systems, and close to the maximum output drawn by any high-end gaming system.

However, the internal fan was noisy from the start, making a high pitched whine even at minimum start speed (at 3V). The volume increased quickly even though the voltage seemed to change fairly smoothly. At full speed, it produced a real racket: 46 dBA@1m. Nevertheless, for many systems the Lion will be effectively silent because the starting point of the fan is so high.

The "Fan Only" output stayed at 5.7-5.8V until the thermistor reached about 55°C. Many low and medium speed fans are very quiet at this voltage, and the 55°C trigger point is high enough that the voltage is unlikely to rise above this level very often. However, the voltage did not rise steadily as the temperature rose. Especially when the temperature was just above the trigger point, the voltage fluctuated quite a bit before it stabilized, may translate into audible "revving" of whatever fans are plugged into the Fan Only headers. Between 55°C and 70°C, the relationship between temperature and voltage was fairly linear, with small increases in temperature translating into corresponding increases in voltage. The "Fan Only" output is useful for quiet thermal control of fans, especially in a low-heat system where the fans would ramp up.

SAMPLE VARIANCE

The first sample we received ran with its fan at full speed, regardless of output load and or the position of the "fan button". The data in our tests comes from a second sample that we requested from ePower.



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