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Enermax Noisetaker II (Rev. 2.2): A New Rev of an Old Fave

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Once upon a time, the Enermax NoiseTaker earned a recommendation from SPCR for being one of the quietest, most efficient power supplies ever. Then the NoiseTaker II was released, which got a less enthusiastic review about a year ago. Now, a new revision of the NoiseTaker II has been released. Can it reclaim the glory of the original version, or have times changed too much for SPCR to approve a dual fan power supply?

May 31, 2006 by Devon
Cooke

Product
Enermax Noisetaker II EG701AX-VE(W)
(Revision 2.2)
600W ATX12V 2.2 Dual Fan Power Supply
Manufacturer
Enermax
Technology Corporation
Market Price
~US$150

Enermax was one of the first companies to sell retail package power supplies and remains a highly visible brand name. SPCR reviewed the original
Noisetaker two years ago
, when low noise was starting to become a popular marketable
feature in power supplies. At the time, it received a glowing review for being quieter and
more efficient than most of the competition.

What a difference two years makes. Were it reviewed today, the original Noisetaker
would not distinguish itself from the crowd. Perhaps that is why Enermax released
the Noisetaker II, which we
reviewed just over a year ago
. That update brought the Noisetaker into compliance
with Intel’s new ATX12V 2.0 specification, corrected a problem with stiff cabling,
and introduced a ferrite ring to reduce EMI.

The latest revision is more of a response to changes in marketing demand than
any technical requirement, althought it is now compliant with Intel’s ATX12V version 2.2 spec. There are more SATA connectors, an additional
PCIe plug for SLI or CrossFire setups, and an EPS12V plug for multiple processors.
Minor changes to the exterior casing and fan controller have also been made.


The retail box has gotten smaller. We like that.


A multi-lingual manual, the PSU itself, screws, a power cable, an Enermax
sticker and… a keychain?

FEATURE HIGHLIGHTS

Feature Highlights of the Enermax NoiseTaker II (from
Enermax’
web site
)
FEATURE & BRIEF COMMENT
Full compliance with the highest standard to desktop power requirements.
Split 12V rails provide most stable current to CPU, GPU, MB and
drives
Split rails have been required
since ATX12V 2.0, and were a feature of the Noisetaker even before then.
Full support of Dual Core
systems (incl. Pentium D EE and Athlon 64 X2) & Dual CPU systems.
Yep. 600W goes a long
way.
Convertible design to power up ATX/BTX systems and support
dual CPU entry-level server/workstation.
Versatility is an asset,
and most of the various specifications are similar enough that a single
power supply works with all of them.
After PC shuts down, cooling fans keep running for at least 30 sec.
to effectively cool down parts and hardware inside PSU and PC case.
Supposedly good for reliability. We’re not sure.
High efficiency of about 80% under wide load range (30-100%)
minimizes your electricity bill.
A feature of the original
Noisetaker.
PF value up to 0.99
to provide stable and clean power under 100-240VAC by auto switching.(AX
models only
)
Active power factor correction.
Protected by OCP, OVP, UVP, OLP, SCP, OTP for maximum safety.
Full rated power under 0-40°C/32-104°F ambient temp.
Over Current Protection,
Over Voltage Protection. Under Voltage Protection, Over Load Protection,
Short Circuit Protection, Over Temperature Protection.
The best cooling method
for PC system
, and is strongly suggested by AMD.
We disagree. Using the
power supply to cool the system often results in a louder power supply.
Manual fan speed control
to keep the balance between cooling effect and acoustic noise. Automatic
fan speed adjustments to prevent system overheat.
Mostly a gimmick, but
could be useful for controlling system cooling.

SPECIFICATIONS

OUTPUT SPECIFICATIONS: Enermax NoiseTaker II
AC Input
100-240VAC 50-60Hz
AC Input Current
9.5~4A
DC Output
+3.3V
+5V
+12V1
+12V2
-12V
+5VSB
Maximum Output Current
34A
34A
22A
22A
0.6A
3.0A

Maximum Combined

180W
420W (35A)
7.2W
15.0W
577.8W
22.2W
600W

The individual line ratings are all quite beefy. Both of the +12V rails have
been bumped up by 4A since the last revision, as has the +5V standby line. However,
the reality is that real limits on output power are most often seen in the combined
power ratings, which have not changed.

The increased capacity on each of the +12V rails is a little bit odd. The sole
reason for having multiple lines is to prevent more than 240 VA (12V ×
20A) from being delivered from a single rail, as per the requirements of UL
and CSA. So why rate the +12V
rails at 22A, which may allow more than 240 VA to flow anyway? Why not
have a single rail rated at 35A?

The answer is most likely political. Enermax can get away with specifying two
+12V rails at 22A each because it is only a minor deviation from the specification.
On the other hand, eliminating the second +12V rail would be a flagrant violation
of the ATX12V specification, and would be frowned on by Intel and anyone else
who reads the ATX12V specifications.

EXTERNAL OVERVIEW

Physically, the new revision looks very similar to its predecessors. It is
the same navy blue with gold fan grills, has the same fan control knob on the
back panel, and uses the same cable sleeving. Cooling is provided by a pair
of fans: A 92mm fan mounted on the bottom, and an 80mm fan to pull the air out
of the case altogether.


Navy blue and gold: Royal colors.

One slight difference is visible on the inside panel: The internal vent has
been shrunk significantly to eliminate the short-circuit in the airflow that
would otherwise have been the result. The photos that follow illustrate the
difference.


The size of the inner vent has been reduced…


…from this size on the last revision.

Aside from the inner vent, the only ways that air can move through the power
supply are through the two fans. The airflow path is as you would expect: Air
is blown in by the bottom fan and is exhausted by the rear fan.


Air flows in at the top and out the back.
The knob by the power switch controls fan speed.

INTERIOR

The internal circuit design has changed very little, if at all. The basic layout
is the same as the previous version, and there are no obvious changes in components.
The layout is also very similar to Enermax’ modular series, the
Liberty
.


The same gold heatsinks we’ve seen in other Enermax power supplies.


Densely packed components do not allow a lot of room for airflow.

The heatsinks themselves are on the small side for such a high capacity power
supply, but the twin fans and back vent should have no problem moving air across
them. The fin arrangement provides plenty of surface area.


Gold heatsinks… and little copper fingers for a particularly hot component.


Active power factor correction.

FANS

Neither of the two fans has changed since the original Noisetaker. Both are
medium speed ball bearing fans labeled "Silence", but aside from that
there’s nothing particularly silent about them. Both are manufactured by Globe
Fan
.


The bottom mounted fan is a 92mm fan with clear fins.


The rear fan does not have clear fins and has a slightly smaller 80mm frame.

The fan control circuit feeds both fans exactly the same voltage, so they speed
up and slow down in tandem. The rear fan is connected with a three-pin fan header
that provides an RPM signal can be passed through to the motherboard. The bottom
fan is not monitored, and uses a simple two pin header.


Both fans can be easily removed thanks to detachable fan headers.

CABLES AND CONNECTORS

The cable sets are arranged into three sleeved bundles which separate out into
individual cable sets. The idea is to keep cables that are likely to be routed
together in a single bundle to ease cable management.

The three bundles contain the following cable sets:

  • Main ATX: fully sleeved
  • +12V AUX, PCI Express, fan RPM: half sleeved
  • Drives: only the first 6" are sleeved.

The individual cable sets are listed below:

  • 23" cable for main 20+4-pin ATX connector
  • 22" cable for auxiliary 4+4-pin +12V AUX connector (Dual CPU compatible)
  • 2 x 22" cable for 6-pin PCIe connector
  • 32" cable with three SATA drive connectors
  • 32" cable with three SATA drive connectors and two 4-pin IDE drive
    connectors
  • 31" cable with three 4-pin IDE drive connectors
  • 31" cable with two 4-pin IDE drive connectors and one floppy connector
  • 28" cable with fan RPM monitor

The main ATX, +12V AUX, and PCI Express cables are all quite long, so they should all reach no matter how large the case. Conversely,
the cables are that much harder to hide if space is limited.

One of the new features of this revision is a cable set that features both
SATA and IDE connectors side by side on the same cable. Enermax has used this
arrangement before on their Liberty power supply. However, unlike the Liberty,
there are also all-SATA and all-IDE cables available. This appears to be an
attempt at a compromise; the cables on the Liberty had both supporters (like
me) and detractors (like MikeC).


IDE and SATA connectors on the same cable.


A ferrite ring is used to reduce EMI and ripple voltage.

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 22°C and 19 dBA, 121V/60Hz.

OUTPUT & EFFICIENCY: Enermax NoiseTaker II (Revision
2.2)











DC Output Voltage (V) + Current (A)

Total DC Output

AC Input

Calculated Efficiency
+12V1
+12V2
+5V
+3.3V
-12V
+5VSB
12.19
0.99
12.17
1.74
5.16
1.00
3.43
0.98
0.0
0.2
42.8
65
66.0%
12.15
1.91
12.14
1.74
5.16
2.00
3.42
1.91
0.1
0.3
63.9
92
69.4%
12.14
1.91
12.12
3.31
5.16
2.00
3.42
3.84
0.1
0.5
90.5
123
73.8%
12.13
3.85
12.10
5.00
5.15
4.82
3.46
3.80
0.2
0.8
151.6
192
78.9%
12.10
5.70
12.06
6.50
5.15
4.71
3.45
5.55
0.2
1.0
198.2
247
80.2%
12.10
6.69
12.06
8.11
5.15
7.41
3.40
6.65
0.3
1.3
249.7
310
80.5%
12.10
7.84
12.05
9.67
5.14
9.23
3.40
8.65
0.3
1.5
299.3
373
80.3%
12.06
11.56
12.00
12.68
5.11
11.02
3.38
11.20
0.4
2.0
400.5
508
78.8%
12.03
15.28
11.98
14.24
5.10
15.10
3.37
14.47
0.5
2.5
498.7
652
76.5%
12.00
17.93
11.93
17.27
5.09
18.30
3.35
18.40
0.6
3.0
598.2
813
73.6%
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: Enermax NoiseTaker II (Revision
2.2)
DC Output (W)
42.8
63.9
90.5
150.6
198.2
249.7
299.3
400.5
498.7
598.2
Intake Temp (°C)
23
25
30
34
35
39
42
48
50
53
Exhaust Temp (°C)
26
28
31
36
40
43
45
51
54
58
Temp Rise (°C)
3
3
1
2
5
4
3
3
4
5
Fan Voltage (V)
3.6~5.1
3.6~5.5
3.6~6.1
4.2~7.5
6.0~9.2
7.4~10.2
8.7~11.4
11.2~11.6
11.6
11.6
SPL (dBA@1m)
24~30
24~32
24~32
26~38
33~42
37~44
40~44
44
44
44
Power Factor
0.97
0.99
0.99
1.00
0.99
0.99
0.99
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. LOW LOAD PERFORMANCE

Power consumption in standby mode was quite low, coming in at ~0.5W
and a power factor of 0.11. However, the power supply would not start properly
with no load applied. In fact, there were problems starting (and staying on)
even with substantial loads on the main voltage lines.

The problem was traced to the two minor voltage rails: -12V and +5VSB. Applying
a small 0.1A load to either of these lines would allow the NoiseTaker II to
function normally. However, removing the load from these lines even for a split
second was a recipe for trouble, as the power supply would either turn off entirely

or rapidly cycle between on and off. We were happy that the
power supply was connected to our test bench, not an actual system when this
happened.

2. VOLTAGE REGULATION was quite good; none of the voltages fluctuated
by more than ±3%. However, all of the voltages were slightly high, especially
the +3.3V line which was typically about 4% above the nominal voltage.

3. EFFICIENCY was about average for a high end power supply. The peak
just barely cracked 80% at the relatively high output load of 250W. This is
an improvement over the earlier version, which peaked at 78.5%. At lower loads,
efficiency was actually quite poor, staying below 70% until ~65W output. Most
systems require less power than this at idle and tend to spend much of their time idling. For this reason, the NoiseTaker II would actually be relatively
inefficient under real world circumstances.

4. POWER FACTOR was excellent thanks to the active power factor correction
circuit. Power factor stayed above 0.97 throughout the testing, which is very
close to the theoretical maximum of 1.0.

5. TEMPERATURE & COOLING

Cooling in the Noisetaker II was not a cause for concern. The internal temperature
rise never rose above 5°C — a very good result. However, the temperature
got quite high in absolute terms. The 53°C intake temperature reached
at the end of the test is well above the 40°C ambient temperature
specified as the maximum operating temperature.

It is a bit difficult to know what to make of the thermal results. There is
only one difference in the cooling system compared to the last version: The
internal vent has been cut down to about half the previous size. Yet, the thermal results of the two
units were quite different. The earlier version that we tested had a higher
temperature rise, which suggests that the change in airflow was beneficial.
On the other hand, the intake temperature, which should not change significantly between tests, jumped up by as much as 10°C.

The implication is that while airflow within the PSU is perfectly adequate for self-cooling, the PSU’s contribution to overall case cooling is lower than before. It suggests that an exhaust fan for the case is very important when using this PSU. This is ironic, considering that Enermax lists its 2-fan system among the features as the best cooling method
for a PC.

6. FAN, FAN CONTROLLER and NOISE

The quality of noise in the NoiseTaker series has never been that good, and
it was an issue once again in the latest revision. There are two major issues:

  1. The fans themselves sound bad, even when running at the minimum speed
    of 3.6V.
  2. The individual fans interact acoustically (intermodulate), creating a dissonant
    motor noise.

The baseline noise level was about 24 dBA@1m. It is quiet, but there are numerous
other power supplies that are quieter. The noise was primarily a two-tone hum
that was the result of the two fans spinning together. A distinct buzz could
also be heard, especially from closer distances.

As the fans speeded up, the two-tone hum quickly became irritating and more
dissonant. The noise had the quality of a train whistle that uses two dissonant
pitches to get attention; unfortunately, attention is exactly what a low noise
power supply needs to avoid.

The fan controller has fallen a bit behind the times. At one time, simply staying
at the baseline level for a while was enough to gain our recommendation, but
times have changed, and there are now much better options available. The fan
began to increase in speed quite early, when the intake temperature was about
34°C. The corresponded to ~150W output — a level that can easily
be exceeded in a system with a hot graphics card.

Those who are inclined to tinker may be interested to hear that the fan control
knob on the back panel allowed about twice the adjustment range as the previous
version. Unfortunately, even the lowest setting was less than satisfactory for
our standards.

Given that the NoiseTaker II is targeted at Dual CPU / Dual VGA systems, it
is hard to imagine that it would be quiet when used as intended.

MP3 Sound Recordings of Enermax NoiseTaker II (Revision
2.2)

Enermax
NoiseTaker II (Rev. 2.2) @ 90W (24 dBA@1m)

Enermax
NoiseTaker II (Rev. 2.2) @ 150W (26 dBA@1m)

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 dBA@1m)

Antec
Neo HE 430 @ 200W (26 dBA@1m)

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

The Enermax NoiseTaker has fallen far, from a star on our recommended list
two years ago to a sub-par performer today. The change is not Enermax’ fault
so much as the result of higher expectations and stiffer competition. Two years ago, quiet, highly
efficient power supplies of the type that we recommend today were very difficult
to find. Now, efficiency and noise have become major selling points, and Enermax
has not kept apace of the changes in the marketplace — at least not with
the NoiseTaker II.

The best things about the NoiseTaker II are the features that prompted the
new revision. The cables are longer and more varied than the previous version,
which should please those who want to run multiple processors. The mixed SATA
and IDE connectors on the same cable is also a nice feature, as is the inclusion
of "plain" cables for those who don’t like the mixed cables. The change
to the exterior casing also seems to have been for the better, as the new version
seems to be better cooled.

Nevertheless, the NoiseTaker is in need of more than just cosmetic changes
to bring it up to current standards. We hope to see a NoiseTaker III with better
quality fans and a low-noise fan controller. Until then, there are better (and
much cheaper) options than the NoiseTaker II.

*

SPCR Articles of Related Interest:
Power Supply Fundamentals & Recommended
Units

Power Distribution within Six PCs
Seasonic S12-430: Our current low-noise champ
Enermax Liberty EL500AWT & EL620AWT Power
Supplies

Enermax NoiseTaker 450 PSU (Original Version)
Enermax NoiseTaker II 600W (The Sequel)

* * *

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

Discuss
this article in the SPCR Forums.

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