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Zalman ZM460-APS Power Supply

Jan 2, 2006 by Devon
Cooke

Product
Zalman ZM460-APS

460W ATX12V 2.01 Power Supply
Manufacturer
Zalman
Market Price US$90~110

Zalman has made a reputation
for itself as a noise-friendly company, so we're always interested when they
release a new product. The ZM460-APS marks Zalman's latest power supply offering.

Zalman's previous power supplies have not been as quiet
as some of its competitors. Compared to the
ZM400B-APS model that we reviewed almost two years ago
, the ZM460-APS is
based on a newer, more efficient circuit design and has a 120mm fan.
It is also compliant with the newer ATX12V 2.01 and sports connectors for all
the latest devices.



As usual, packaging is slick and lists the specifications and features
on the side of the box.



Lots of extra goodies.

You pay a bit of a premium for the Zalman name, but there's
some compensation in the number of extras included. In addition
to the AC cable, mounting screws, and the power supply itself, there are several
other items:

  • a well-illustrated manual with more technical information than usual (including
    cable lengths!)
  • some velcro ties for cable management
  • a Y-adaptor for the PCIe connector, allowing SLI systems to be used
  • a Y-adaptor from Molex to 2 x SATA connectors to increase the number of
    SATA drives that can be powered
  • a Y-adaptor from Molex to 2 x 12V fan headers and 2 x 5V fan headers to
    power (or undervolt) system fans

FEATURE HIGHLIGHTS


Feature Highlights of the Zalman ZM460-APS (from Zalman's
web site
)
FEATURE & BRIEF COMMENT
CNPS (Computer Noise Prevention System) with Auto Control Cooling
Fan
Fancy talk for a thermally
controlled fan controller.
Improving Power Factor
& Eliminating Harmonics through Active PFC:
By implementing Active
PFC, the power factor (PF) is improved from 75% (Passive PFC) to 96% (230VAC,
Full load), while harmful harmonic frequencies are reduced below regulatory
requirements.
Power factor correction
reduces the AC amperage required and can reduce power costs for people billed
by VA instead of wattage.
High Efficiency Design: Designed with a high switching frequency
and low power-loss circuitry, the efficiency of this product exceeds 80%
(230VAC, Full load).
Most high-end power supplies
can hit 80%, though not all can do it at full load. Note the 230VAC input; it's usually 2~3% less efficient at 110~115VAC.
ATX ?20+4?-Pin Main Connector: ATX ?20+4?-Pin
main connector broadens mainboard compatibility.
Compatibility with older
motherboards.
ATX12V CPU (4-Pin) & EPS12V CPU (8-Pin) Connectors: Use two
ATX12V 2x2(4-pin) connectors together to form an EPS12V CPU connector(8-pin).
EPS12V is a standard
for server and workstation computers, which often have multiple processor
chips and require more power.
PCI Express Graphic Card
Power Connector(6-Pin):
PCI-Express graphics card power connector is
provided to high-end graphics card support.
Almost a standard feature
now.
EZ Grip Connectors for ODD & HDD: EZ Grip Connectors for ODD
& HDD for easy connecting and disconnecting of the plugs.
Much easier to unplug
than standard connectors...
Dual +12VDC Output: Two
+12VDC rails output up to 30A combined, providing more stable power to high-end
systems.
Required by ATX12V 2.01
Sleeved Cables: All
power cables are sleeved for easy cable management and improved air circulation
in thecomputer?s case.
Good for cable management,
but mainly for aesthetic purposes.
Certified
with International Safety Approvals & EMC Standards:
CE, CB, RU,
MIC, FCC
The more
the better...
Strict DC Voltage Regulation
& Low Output Ripple / Noise
The basic electrical
goal of any power supply: Voltage regulation and Low ripple.

OUTPUT SPECIFICATIONS


SPECIFICATIONS: Zalman ZM460-APS (from Zalman's
web site
)
AC Input
110~240 VAC ±10% / 47~63 Hz
AC Input Current
7.5 @ 115VAC / 3.5A @ 230VAC
DC Output

+3.3V

+5V

+12V1

+12V2

-12V

+5VSB

Maximum Output Current

28A

30A

16A

18A

0.8A

2.0A

Maximum Combined
180W
360W
9.6W
10W

460W

460W of capacity is a lot of power to play with. The ZM460-APS should have
no problem keeping up with the big boys. Most of the current is available where
it's needed ? the +12V rails ? so getting enough power should not
be a problem. It shouldn't have any problem sustaining it either: Its maximum
operating temperature for rated power output is 50°C.

PHYSICAL BASICS

The matte black finish is sleek and sedate, which gives it a sense of style
(which is good) without being flashy (which is also good). The sleekness is interrupted
by several small stickers that confirm the safety testing and list a few of
the unit's more notable features. The spec sticker on the side is especially
large ? so large that it partially obstructs three small vents along the
top edge.



Sleek, black, and covered with stickers.

On the whole, the ZM460-APS is well ventilated. The rear grill is very
open, the intake is covered by an unrestrictive wire grill, and there are a
few small vents on the side and the back to relieve back pressure from the fan.
Regular readers may recognize
the casing from the FSP Green PS
, which has an identical layout. (It's
not black, though).



The rear grill is wide open ? good for cooling.

INSIDE

The circuit appears very simple; the internal components take up
about half the room of an ordinary power supply of this power rating. And, if the size of the heatsinks
are anything to judge by, they are packed loosely enough that they require less
airflow than usual to cool.



A small, simple PCB with a sparse layout.

As you can see from the photos below, the resemblance to the FSP Green PS continues
inside. The layout, the color of the PCB, and the
style of the heatsinks are all very close. It's no secret that Zalman has sourced
their power supplies from FSP in the past, and a direct comparison of the two
shows that this partnership has continued. This is a good thing; the Green PS
did well on our test bench. The drawback with the Green PS was its availability;
Zalman's widespread distribution should make the ZM460-APS easier to get hold
of than the Green PS.



Two of the heatsinks are simple aluminum plates; the third has only a
few simple fins.

Aside from some fairly minor differences in the specific ratings of the internal
components, the main difference between the Zalman and the Green PS is the heatsink that cools the main transformer and the voltage regulation components.
In the Green PS, this heatsink is a simple plate. The Zalman adds twelve
short fins, each about half a centimeter long. This is far from a large difference,
but it is probably what allows Zalman to squeeze an extra 60W of output from the design. This heatsink is screwed directly to the rear of the power supply, using the
casing as an extension of itself. This means the heatsink can be smaller, and
thus allow air to flow around it more easily.



The layout is almost identical to the FSP Green PS shown above. The size of the third
heatsink is the only obvious difference.

Despite its small heatsinks, the cooling in the Green PS held up admirably
when we tested it, and we expected the Zalman to perform similarly. The
key to its design may be the sparse interior layout, which allows much more
airflow than usual to pass through.

FAN



Zalman has used NMB fans in their past products.

You wouldn't know it from the model number, but the fan is a low speed, dual
ball bearing model. The current rating on the label (0.25A) does not match any
of the (numerous) spec
sheets
I was able to find (0.19A), but fans of this rating tend to be low
to medium speed.

CABLES AND CONNECTORS

There are a total of seven cable sets and three adapters, all of which are
sleeved in black nylon mesh. Zalman is one of the few brands that lists
the length of each cable in the manual
, so we were saved the trouble of
measuring them ourselves. As mentioned already, there are several adapter cables
included that allow unusual configurations without cluttering up the design
with extra cable sets.

  • 21" (550mm) cable for main 20+4-pin ATX connector
  • 21" (550mm) cable for auxiliary 4+4-pin 12V AUX connector (ATX12V/EPS12V
    compatible)
  • 21" (550mm) cable for 6-pin PCIe connector
  • 21" (400 + 150mm) cable with two SATA drive connectors
  • 2 x 33" (550 + 150 + 150mm) cable with two 4-pin IDE drive connectors
    and one floppy connector
  • 33" (550 + 150 + 150mm) cable with three 4-pin IDE drive connectors
  • ??" PCIe splitter for dual VGA systems
  • ??" IDE to 2 x SATA adapter for drives
    with three or more SATA drives
  • ??" IDE to 3-pin fan header adapter (2
    x 12V, 2 x 5V)

The cables are of average length, but, thanks to the extra adapters, there
are relatively few in total. This should be good for cable management, as there
will be less extra cables that need to be hidden away in the final build. Very
few people are likely to use all of the available connectors, and even fewer
will need the adapters.

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 20°C and 20 dBA, 121W/60Hz.

OUTPUT & EFFICIENCY: Zalman ZM460-APS











DC Output Voltage (V) + Current (A)

Total DC Output

AC Input

Calculated Efficiency
+12V1
+12V2
+5V
+3.3V
-12V
+5VSB
12.24
0.97
12.22
1.74
5.10
0.99
3.34
0.00
0.1
0.2
40.4
62.1
65.0%
12.25
1.92
12.23
1.74
5.09
1.96
3.33
1.86
0.1
0.3
63.7
89.1
71.5%
12.23
1.91
12.20
3.32
5.08
2.91
3.3
2.75
0.2
0.4
92.2
122.2
75.5%
12.21
4.80
12.20
3.32
5.05
5.66
3.31
4.55
0.3
0.7
149.9
190.4
78.7%
12.19
5.74
12.16
5.01
5.03
7.28
3.31
7.51
0.4
0.9
201.7
249
81.0%
12.16
7.82
12.12
6.47
5.01
8.17
3.30
7.49
0.4
1.1
249.5
308
81.0%
12.13
8.76
12.08
8.12
4.99
10.70
3.28
9.13
0.5
1.3
300.2
373
80.5%
12.14
10.59
12.04
11.23
4.94
14.61
3.26
14.05
0.7
1.7
398.6
508
78.5%
12.08
13.31
12.00
12.60
4.92
16.19
3.25
15.53
0.8
2.0
461.7
599
77.1%

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: Zalman ZM460-APS
DC Output (W)
40.4
63.7
92.2
149.9
201.7
249.5
300.2
398.6
461.7
Intake Temp (°C)
21
24
28
31
35
38
40
44
45
Exhaust Temp (°C)
26
30
32
37
41
45
48
54
59
Temp Rise (°C)
5
6
4
6
6
7
8
10
14
Fan Voltage (V)
4.6
5.0
5.4
6.3
7.2
8.2
9.1
11.0
11.0
SPL ([email protected])
21
22
23
26
29
31
34
37
37
Power Factor
0.93
0.95
0.96
0.98
0.97
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, within ±2% throughout the
test. Voltages tended to be slightly above nominal, but this is true of many
power supplies.

2. EFFICIENCY was also very good. The peak value of 81% was reached
between 200-300W output. The efficiency slope was quite steep at lower outputs,
and efficiency was not as good in the low end. However, in the range that most
systems will be operating, it was always above 70%. This is still good performance,
but a better results might be had from a power supply that is designed for lower
loads.

A comparison with the FSP Green PS shows that the shape of the efficiency curve
is almost identical, but the lower capacity of the Green PS means that it starts
at a higher efficiency and reaches its peak efficiency sooner.

3. POWER FACTOR was excellent thanks to the active power factor correction
circuit. Power factor stayed above 0.93 throughout the testing, which is very
close to the theoretical maximum of 1.0.

4. TEMPERATURE & COOLING

Like the Green PS, cooling performance was solid but unremarkable. The temperature
rise stayed close to 6°C through most of the usable output range. Above
300W output, the temperature rise increased significantly, but it never got
high enough that safety was a concern. The intake temperature always remained below 50°C, so the ZM-460APS
was running within its maximum operating temperature.

5. FAN, FAN CONTROLLER and NOISE

The fans in Zalman's past power supplies have not been especially quiet, but
this 120mm NMB-MAT fan is one of
the smoothest power supply fans we've heard. In fact, at its lowest speed, it
was smoother and quieter than the Seasonic S12. Considering that the S12s have the top spot for quiet fan-cooled PSUs, that's quite
a compliment.

At minimum speed, the fan was very close to inaudible; only a faint background
hum could be heard. The fan was obviously running very close to minimum speed
as a slight "chugging" could be heard at a close distance. As the
intake temperature increased, the hum gradually increased in intensity until
it was clearly audible with the intake temperature somewhere around 30°C.
Changes in pitch and intensity were very gradual.

Unfortunately, the fan controller in the ZM460-APS didn't quite meet the same standard as the fan, so it will probably be a little louder than
the Seasonic S12s in actual use. Even though it wasn't on par with the champ, it
was still not bad and is quite different from the controller in the Seasonic.

Most fan controllers stay at a single level until a certain thermal threshold
has been reached, when the fan speed begins to increase. The fan curve is basically a straight horizontal line which tilts upwards at the trigger temperature. Better PSUs
increase the fan speed over a longer period of time, and utilize good heatsinks to ensure that the maximum fan speed is not reached until
a very high output level. The advantage of the this design is that the fan tends
to stay at very low speed almost all the time.

Zalman's fan controller changes almost linearly with the intake temperature.
In general, this is not as good an approach as the hinged fan curve described above. In practice, changes in the Zalman's fan speed tended to be very, very slow. However,
it was always changing very slightly to compensate for slight changes in temperature,
so the sound was not as steady as other power supplies. Whether this fan noise variability is audible will depend on the rest of the system and on the ambient room noise.

Overall, the Zalman managed to stay below our arbitrary "quiet" level
of 30 [email protected] until it reached 250W output ? albeit at a coolish 20°C room ambient, which probably helped a bit. This is still very good performance, and
a decided improvement over Zalman's previous effort.

MP3 Sound Recordings of Zalman ZM460-APS

Zalman
ZM460-APS @ 40W (21 [email protected])

Zalman
ZM460-APS @ 65W (22 [email protected])

Zalman
ZM460-APS @ 90W (23 [email protected])

Zalman
ZM460-APS @ 150W (26 [email protected])

Zalman
ZM460-APS @ 200W (29 [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])

Nexus
92mm case fan @ 5V (17 dBA/1m) Reference

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.

COMPARISON

For some time now, our standard for a quiet power supply has been the Seasonic
S12 series
, which combines an excellent fan with an excellent fan controller.
The Zalman is also quite good, so it is worth comparing the two to see just
how they differ. The FSP Green PS was also included in the comparison because
of its similarity to the Zalman. The data in the following table has been taken
from the reviews for the FSP
Green PS
, the Seasonic
S12-430
and the Seasonic
S12-500/600
. For the S12-430, the data for the most recent revision
was used.

SPL Comparison (in [email protected]): Zalman ZM460-APS vs.
Seasonic S12
Target Output Power
65W
90W
150W
200W
250W
300W
Zalman ZM460-APS

(Ambient 20°C/20 [email protected])
22
23
26
29
31
34
FSP Green PS FSP400-60GLN

(Ambient 20°C/19 [email protected])
25
26
29
31
34
37
Seasonic S12-430 (Rev. A2)

(Ambient 21°C/19 [email protected])
20
20
22
25
29
32

Seasonic S12-500 (Rev. A2)

(Ambient 21°C/18 [email protected])
21
21
22
25
28
34

It should be noted that the ambient noise level in this comparison puts the
Zalman at a slight disadvantage, but not so much that it changes the result.
Add and subtract appropriately if the specific numbers mean that much to you.

At the lower output levels, the noise levels are pretty close, although the Seasonics
are still a bit better. At 40W output, the Zalman may have been better, but
as the Seasonics were not tested at this level it is impossible to say for sure.
The difference is biggest between 150-200W output, but the Zalman manages to
catch up by the time the output reaches 300W, where the difference is too close
to call. They're all too noisy by this power output level, anyway.

In spite of the almost identical circuit design and fan controller, the Zalman
was clearly quieter than the Green PS. The difference is due almost completely
to the different fan that Zalman has used.

CONCLUSIONS

The ZM460-APS should go a long way towards cementing Zalman's reputation as
one of the most noise-conscious PC component companies. It should also help overturn
the relatively poor reputation of Zalman's past power supplies. Although it
is not quite on the same level as our perennial favorite, the Seasonic S12,
it does do quite well, and has a smoother fan to boot. It also features a couple
of added features over the S12-430, notably sleeved cables and, thanks to the
included adapters, more SATA and PCIe connectors.

Both efficiency and voltage regulation are very good, so there's nothing to
worry about in the electronics department. The only sticking point
is the price. At >$90, the ZM460-APS is among the priciest PSUs in its power category. But the Seasonics are pricey too: The S12-430 sells for a bit less, but the S12-500 sells for >$100 just about everywhere.

If noise is
the main concern, the Seasonic is still a winner, but the differences are small
enough that price and availability may be the deciding factors. Even if Zalman
doesn't have a clear champion, they have a worthy competitor.

* * *

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

Discuss this article in the SPCR Forums.

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