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SilverStone Strider ST56F power supply

January 15, 2006 by Devon
Cooke

Product
SilverStone Strider ST56F

560W Power Supply
Manufacturer
SilverStone
Technology Co. Ltd.
Market Price
US$120~130

"Strider" is an odd word to name a power supply. It brings to mind
the dour warrior from Lord of the Rings movies. Maybe that's the image
SilverStone is going for: The strong, silent type. With a capacity of 560W,
it should certainly be strong enough. The question is, will it do steadfast
battle without making excessive noise, or will it charge in with its fan screaming
a battlecry?

SilverStone is best known for its high-end cases, such as the Temjin
TJ-06
, or the Lascala LC-11, but they
also sell a large range of power supplies. Despite its substantial price and
heavy-duty construction, the Strider 560W belongs to SilverStone's "basic"
line. Other lines include the Zeus, for workstations, and the fanless
Nightjar
.



The retail box is simple and classy...



...and the contents are equally Spartan.

FEATURE HIGHLIGHTS

Feature Highlights of the SilverStone Strider ST56F
(from
SilverStone's
web site
)
FEATURE & BRIEF COMMENT
Efficiency over 80%
The manual says "Greater
than 80% typical at normal AC main voltage and full load on all output"...
can it do it?
Dual +12V rails
for advanced systems
A standard requirement
of ATX12V
Dual PCI-E connectors
Standard for SLI & CrossFire support.
Silent running 120mm fan
No running fan is truly
silent... but we'll settle for quiet.
Support for ATX 12V 2.01 & EPS 12V
"Support for"
= Compliance?

OUTPUT SPECIFICATIONS

SPECIFICATIONS: SilverStone Strider ST56F (from SilverStone's
web site
)
AC Input
90~264 VAC / 47~63 Hz
AC Input Current
10A @ 100VAC / 5A @ 240VAC
DC Output
+3.3V
+5V
+12V1
+12V2
-12V
+5VSB
Maximum Output Current
30A
30A
18A
18A
0.5A
2.0A
Maximum Combined
180W
432W
6.0W
10.0W
560W

In addition to the usual marketing blurbs, SilverStone's web site includes
extremely comprehensive technical specifications. In fact, the
manual
reads as if it has been adapted from the official ATX12V
spec document
. This makes comparing the two side by side quite easy, and
— uh oh — not all of the specs seem to be in compliance. In fact,
the ATX12V and EPS12V standards are not even mentioned in the manual. The only
place these standards are mentioned is under "special features" on
the product page itself, where it reads "Support for ATX 12V 2.01 &
EPS 12V".

The violation of the ATX12V spec is fairly minor: 80 mV ripple on the +3.3V
rail instead of the required 50 mV. In reality, it is very difficult to judge
whether this variation will make any meaningful difference in the operation
of the power supply.

  • SilverStone's engineers might just be very conservative. After
    all, 80 mV is the listed specification, but this amount of ripple
    may only occur under very specific extreme circumstances. This is often
    the case; ripple tends to increase when the load across the lines is very unbalanced,
    which is an unrealistic scenario.
  • Even if it does violate the ATX12V spec, it is unlikely to cause problems
    unless it is used with hardware that is particularly sensitive
    to ripple on the +3.3V line, or under circumstances (mainly overclocking) where
    excess ripple may cause instability.
  • Because many manufacturers don't declare ripple, it is hard to know how
    common this particular violation is.

When it comes down to it, the high ripple spec is probably only a problem on paper.
It seems reasonable to give SilverStone the benefit of the doubt
and agree that the Strider has "support for" ATX12V even if it doesn't
strictly comply with it. It is worth noting that the Strider does not
show up on any of Intel's
ATX12V Tested Power Supply Lists
.

The violation of EPS12V is a little more serious: EPS12V requires tighter (±3%)
voltage regulation and at least three +12V rails. But, as with the first violation,
this is mainly a problem on paper. We often see ±3% regulation even on
units that don't declare it, and the
issue of multiple rails has very little to do with how a power supply actually
performs
(in most cases it only affects the over-current protection circuitry).
In addition, there are many, many
other examples of power supplies that support the EPS12V motherboard connectors
without actually complying with the standard.

PHYSICAL BASICS

The Strider wears a sleek coat of matte black (and lead-free!) paint. A matching
black fan, black fan grill, and black cable sleeving give it an almost military
appearance.



Airflow looks excellent from this side...



...and nonexistent on this side.

The internal airflow is wholly conventional: Air goes in the bottom and comes
out the back. There are no auxiliary vents on any of the other panels. Given
the high capacity of our sample, cooling could become an issue at higher output
levels, since this kind of closed design can lead to pockets of dead
air in the corners.



The intake is very unrestrictive.

(Yellow wire not included; it was added for testing purposes.)

To make up for the lack of exhaust vents elsewhere, the rear panel is completely
open. Even the small spaces above the switch and power socket are perforated
with hexagonal holes.

CABLES AND CONNECTORS



Cables sets are numerous, and the IDE cables are quite long.

There are a total of nine cable sets. All cables except SATA and IDE cables
are sleeved in black nylon mesh.

  • 22" sleeved cable for main 20+4-pin ATX connector
  • 19" sleeved auxiliary 4-pin 12V AUX connector
  • 19" sleeved auxiliary 8-pin 12V EPS AUX connector
  • 2 x 19" sleeved cable for 6-pin PCIe connector
  • 2 x 29" cable with two SATA drive connectors
  • 2 x 41" cable with three 4-pin IDE drive connectors and one floppy
    connector

The selection of cables is fairly typical for a unit of this capacity. Dual
PCIe connectors allow SLI and Crossfire compatibility out of the box. The connectors
are not on the same cable, which is a slightly safer arrangement, but is more
prone to cable clutter.

Four SATA connectors make sure that modern multi-drive setups are also well
supported. The longest (and, now that most drives are SATA, most useless) cable
sets are the IDE cables, which sport three IDE power connectors and a floppy
connector each.

INSIDE THE STRIDER

There are two aluminum heatsinks with large, finger-like
fins that extend above the components below. The heatsink design is very simple,
and despite their large size, they don't have a lot of surface area.
On the other hand, the wide spacing between the fins should be good for low
airflow cooling, and should help cut down on airflow impedance. There is a small
gap between the end of the PCB and the rear grill, which suggests that the Strider
was adapted from a model with an 80mm fan.



The heatsinks have large aluminum fingers.

The main transformer and the input capacitor are both very large — so
large that the heatsinks do not have room for fins above them.



SilverStone calls these "Industrial Grade Components". I call them
a PFC coil and a smoothing capacitor.

The fan appears to be made by Adda. It is a sleeve bearing, "low noise"
design, but the 0.4A rating indicates that it is also capable of high speed. Adda fans appear in some of the quietest
power supplies, but those fans tend to be low or medium speed
models. The level of noise will depend a lot on how low a voltage the fan
receives from the fan controller.



High speed doesn't look promising for low noise.



A standard 2-pin fan header should make fan swaps easy.

If the fan turns out to be loud, it won't be difficult to swap. The fan uses a standard 2-pin header that is conveniently located at the
front edge of the PCB.

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

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 ([email protected])
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.

MP3 Sound Recordings of the SilverStone Strider ST56F
(560W)

SilverStone
Strider ST56F @ <150W (24 [email protected])

SilverStone
Strider ST56F @ 200W (28 [email protected])

There was no need to make recordings at higher power
levels; it's simply too loud.
Sound Recordings of PSU Comparatives

Seasonic
S12-430 (Rev. A1) @ 150W (19 dBA/1m)

Seasonic
S12-430 (Rev. A1) @ 250W (26 dBA/1m)

Antec
Neo HE 430 @ 150W (21 [email protected])

Antec
Neo HE 430 @ 200W (26 [email protected])

HOW TO LISTEN & COMPARE

These recordings were made
with a high resolution studio quality digital recording system. The microphone
was 3" from the edge of the fan frame at a 45° angle, facing the intake
side of the fan to avoid direct wind noise. The ambient noise during all
recordings was 18 dBA or lower.

To set the volume to a realistic level (similar to the
original), try playing the Nexus 92 fan reference recording and
setting the volume so that it is barely audible. Then don't reset the
volume and play the other sound files. Of course, tone controls or other
effects should all be turned off or set to neutral. For full details on
how to calibrate your sound system to get the most valid listening comparison,
please see the yellow text box entitled Listen to the Fans
on page four of the article
SPCR's Test / Sound Lab: A Short Tour.

CONCLUSIONS

So, is the Strider truly the strong and silent type? Well, it's certainly strong.
Voltage regulation was tight, output capacity was impressively high, and efficiency
was the third highest we've measured.

But silent? Hardly. Quiet, maybe, but there are quieter PSU options.
Silencing the Strider would not be difficult. The high speed fan is an excellent
candidate for a fan swap. The Strider uses a standard fan connector that is
easily accessible, so the operation itself should be quite easy.

The obvious problem with a swap to a slower, quieter fan is potential overheating if the PSU is asked to deliver anywhere near its rated power. Just keep in
mind that using a fan with lower airflow will probably reduce the maximum safe output capacity, as cooling at the higher loads was not the best we've seen.

For those who are not quite so concerned with noise as the average SPCR visitor, the Strider is a fine PSU. But for most SPCR regulars, there are probably better ways to spend $130
if you want a quiet, high power PSU. The Strider's strengths
are not quite enough to overcome its weaknesses — a bit too much noise beyond middling loads and less than ideal cooling at more than 50% load. If
it was cheaper, a fan swap might be a viable
option, but SilverStone is a premium brand, with prices to match.

* * *

Much thanks to SilverStone
for the opportunity to examine this power supply.

Discuss this article in the SPCR Forums.

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