SilverStone Strider ST56F 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 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...

Ambient conditions during testing were 21°C and 19dBA, 119~121V/60Hz.

OUTPUT & EFFICIENCY: SilverStone Strider 560W
DC Output Voltage (V) + Current (A)
Total DC Output
AC Input
Calculated Efficiency
+12V1
+12V2
+5V
+3.3V
-12V
+5VSB
12.20
0.96
12.19
1.73
5.07
0.98
3.38
0.97
0.0
0.1
41.5
59.4
69.9%
12.21
1.91
12.20
1.73
5.06
1.93
3.37
2.80
0.1
0.2
65.8
87.4
75.3%
12.21
1.90
12.19
3.30
5.06
2.87
3.35
2.76
0.1
0.3
89.9
114.6
78.4%
12.17
3.80
12.15
5.00
5.05
4.66
3.35
4.64
0.1
0.5
149.8
185.7
80.7%
12.15
6.61
12.14
4.99
5.04
6.42
3.34
6.25
0.2
0.7
200.0
242
82.7%
12.14
7.75
12.12
6.48
5.04
8.15
3.32
8.41
0.2
0.9
248.5
304
81.7%
12.12
8.70
12.10
8.12
5.02
10.71
3.30
10.04
0.3
1.1
299.7
372
80.6%
12.07
11.39
12.04
11.22
5.04
13.90
3.30
14.18
0.4
1.4
401.1
516
77.7%
12.06
14.12
12.01
14.24
5.05
17.12
3.29
17.22
0.5
1.8
499.4
665
75.1%
12.08
15.98
12.00
15.73
5.01
19.35
3.28
19.32
0.5
2.0
558.1
765
73.0%
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: SilverStone Strider 560W
DC Output (W)
41.5
65.8
89.9
149.8
200.0
248.5
299.7
401.1
499.4
558.1
Intake Temp (°C)
21
22
25
28
29
29
30
34
38
41
Exhaust Temp (°C)
26
30
32
37
40
42
45
51
56
61
Temp Rise (°C)
5
8
7
9
11
13
15
17
18
20
Fan Voltage (V)
4.7
4.7
4.8
4.8
5.6
7.3
9.2
12.0
12.0
12.0
SPL (dBA@1m)
24
24
24
24
28
36
40
44
44
44
Power Factor
0.98
0.99
0.99
0.99
0.97
0.98
0.98
0.99
0.99
0.99
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 very good, staying within ±2% on the +12V and +5V rails and ±3% on the +3.3V rail. Voltages were closest to nominal at full load, and only the +3.3V rail ever dropped below nominal. This result helps supports Silverstone's claim for EPS12V support.

2. EFFICIENCY

The efficiency curve of the Strider was very steep ranging from 70% at 40W, up to 83% at 200W, and back down to 73% at full load. Overall, the efficiency is quite good, but there's no question that it's best in the middle. Fortunately, the peak efficiency is reached where it matters most: In the 200-300W range where most high performance desktops draw peak power.

83% peak efficiency is top-tier performance; SilverStone is right to brag about the efficiency of the Strider. However, their claim of 80% efficiency at full load could not be confirmed; our sample fell to 73% efficiency at 560W. Given the very steep drop in efficiency after the peak, the tough thermal conditions of our testing procedure may have caused efficiency to drop more than it would in a test where the intake is fixed at a lower temperature.

To put this in perspective, several other power supplies with top-tier efficiency were compared for minimum efficiency, maximum efficiency, and efficiency at full load.

Highly Efficient Power Supplies (Ranked by Maximum Efficiency)
Model
Minimum
Efficiency
Maximum
Efficiency
Efficiency
@ Full Load
Seasonic SS-400HT 80 Plus
77%@40W
85%@150W
83%
FSP Zen 300W
77%@40W
85%@150W
83%
SilverStone Strider 560W
70%@40W
83%@200W
73%
Antec Phantom 500W
75%@40W
83%@250W
78%
Seasonic S12 430W
76%@430W
82%@200W
76%

As the table shows, the Strider is tied for the third most efficient power supply we've tested when sorted by peak efficiency. However, its minimum efficiency and efficiency at full load are well below the other units on the leaderboard .

3. POWER FACTOR may have been the best we've ever seen. Even at the low output of 40W, the power factor was 0.98. There was no curve to speak of, power factor remained at 0.98 throughout testing.

4. TEMPERATURE AND COOLING

Thermal performance was good enough though most of the lower output range, but showed signs of struggle as the power output increased. The thermal rise between intake and exhaust never really stabilized, and hit a whopping 20°C at full load. By this load, the fan had been spinning at full speed for some time. It seems likely that the increase in temperature may have contributed to the large drop in efficiency seen above 400W. In comparison, most of the other PSUs we've tested at this load have shown a thermal rise of 10~15°C.

It's difficult to know exactly why the thermal rise was so high, but here are some possibilities.

  • The heatsink surface area is too small to dissipate the excess heat.
  • The airflow is not effective enough to evacuate all the heat.
  • The density of the components creates too high an impedance for effective airflow.
  • All of the above.

However, even with the high temperature at full load, none of the voltage lines showed signs of instability. At this point, the intake temperature was 41°C. Given the tolerance of our thermal measurements, the Strider was at its 40°C rated maxiumum operating temperature.

5. FAN, FAN CONTROLLER and NOISE

The basic noise character of the fan was not bad, but it spun too fast to be considered quiet compared to most of the competition. The default noise was a smooth purr that blended easily into the background in spite of its volume. At faster speeds, the noise was also quite smooth, but it quickly became too loud.

One trait marred the overall smoothness of the sound. There was an odd, pure overtone that could be clearly heard when the fan voltage was between 5.3~5.4V. Outside of this voltage range, no resonant tone could be heard. This tone was probably unique to our particular test setup, but other systems may have other resonant tones.

The fan spun at minimum speed until the internal temperature rise was ~10°C, when it began to spin up sharply. The rate of increase was quite fast, but did not vary too much. Changes in fan speed were clearly noticeable, but once the fan found its new speed it tended to stay there until the next large change in temperature.

Perhaps because it was spinning so fast to begin with, the fan did not ramp up until relatively late in the test: The first measurement point above minimum was 200W, which is above the maximum power potential of all but a high-end or gaming system.



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