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Enermax NoiseTaker 475 PSU

March 24, 2004 by Mike Chin

Product
Enermax NoiseTaker EG475P-VE SFMA

470W ATX 12V v1.3
power supply
Manufacturer
Enermax
Sample Supplier
Maxpoint
Market Price
~US$100

Enermax is one of the very first names that comes to mind when you think of computer power supplies. They were the first to merchandise the power supply as more than a gray mysterious gray box that hums in the back of the PC. With their signature metallic blue paint job, dual-fans and wire grills, they have long been among the most visible of PSU brands.

The first Enermax PSUs I used and examined starting about three years ago did not fare well for PC silencing, despite the whisper quiet promise of their marketing. The fans started off at a very quiet level but then ramped up to much higher speed, due mostly to a fan controller that increased fan speed linearly with internal temperature. One of SPCR's first articles was an examination of how to change this fan speed behavior in the Enermax and other thermal fan PSUs.

Technology companies can never stand still, and Enermax is no exception. They have made changes to their extensive PSU product range. A new series, called NoiseTaker, is named for what it is supposed to do: Take the noise away. Maxpoint, the US distributor, suggested it was time for SPCR to take another good look at Enermax, and sent over a NoiseTaker EG475P-VE SFMA 470W ATX 12V v1.3
power supply.

As you can see, looks have not changed much. It is still that nice metallic blue, and the recessed wire grills are still gold-colored.

This new power supply has many strong features, and a 3-year warranty for all units purchased after February 1, 2004. Among the feature highlights:

FEATURE & BRIEF COMMENT
Smart fan: After PC shuts down, cooling fans
keep running for at least 2 minutes to effectively cool down
parts and hardware inside PSU and PC, ensuring
longer product life.
It is not clear whether this is truly a useful feature, but it probably can't hurt.. Perhaps for hot PCs in hot environments...
Separate 12V rails: Two independent
12V rails supply to MB/CPU and drives in order to provide
stable and clean current to noise-sensitive devices, such
as: CPU, add-on cards. Meets UL 240VA safety requirements
An interesting twist on independent 3.3V, 5V and 12V rails. With power-hungry VGA cards and CPUs drawing on the 12V line, two independent 12V lines is probably a good idea.
ATX 12V V1.3 compatible: Support
latest P4 and Athlon 64 platforms. For P4 platforms use
865 (Springdale) & 875 (Canterwood) chipsets and even
new P4 Prescott and AMD Athlon 64 or later CPU.
This is only the 2nd PSU line we've looked at that is V1.3 compatible (the first being the Seasonic Super series); generally a good thing, with higher current capacity for the 12V line.
S-ATA connectors: Connect your
system to the faster S-ATA interface for better performance.
Two on one lead, obviously useful.
Manual and automatic fan speed
control:
8cm & 9cm fans automatically controlled
by thermostat plus rheostat control over 8cm fan. Enable
users to keep the balance between cooling effect and acoustic
noise.
The range of the manual controller is affected by the thermistor: Both maximum and minimum speeds ramp up and down with temperature.
Extra Power connector: Extra
4-pin power connector provides high-end graphic card with
stable current.
This appears to be dedicated, but it is just a single lead in a more insulated cable.
Reliability: OCP, UVP, OVP,
OLP, OTP, and SCP circuits ensure system well-guarded from
any dangers. Maximize safety for your hardware and valuable
data.
Generally, the more safety approvals the better. Means good international distribution, at least.
Copper-shielding: Effectively
reduces electro-magnetic interference that might affect
MB and CPU from normal operation. (Valid for models with
370W and higher total power)
Not sure where this copper is. In the cable braiding?
Dual Fan: The best cooling
method for PC system, and is strongly suggested by AMD.
SPCR doesn't regard the dual-fan design so highly, but the proof is in the noise and the cooling.
Silence: Acoustic
noise is successfully reduced with two fans giving more
airflow in less rpm and smooth mechanical design of fan
guards.
See comment directly above.
FM & FC functions:
RPM signal of 8cm exhaust fan is provided; EG xxx AX-VE
SFCA/FCA models allow MB to on/off control 8cm exhaust fan.
MB control is an interesting function; not on this sample.

And the official NoiseTaker Specifications:

AC Input
95V~135V or 180V~265V (selected by slide switch)

47~63 Hz;
60A max. on cold start
DC Line
+3.3V
+5V
+12V1
+12V2
-12V
+5Vsb
Ripple
50mV
50mV
120mV
120mV
120mV
50mV
Tolerance
°5%
°5%
°5%
°5%
°10%
°10%
Output
34A
40A
16A
15A
0.8A
2.5A
Combined
280W
372W (31A)
9.6W
7.5W
Total
460W

It is a powerful unit according to the specs. 372W on the 12V lines alone is a lot of power. But note that the numbers on the left don't add up to 470W. This means 372W on the 12V line is available only if the rest of the lines are putting out 98W or less. Conversely, 280W is available on the 3.3V and 5V lines only if the other lines are not drawing more than 190W.

Interestingly, the operational temperature is given as 0~40°C. This is much stronger than what is specified for most Enermax PSU models:

"0 ~25°C for full rating of load, decrease to 80% rating of load at 40°C; decrease to zero Watts O/P at 70°CC"

If the unit can really deliver 470W at 40°C, it is a very powerful power supply.

FAN CONTROLLER

This feature is one of the most important from a silencing point of view. As mentioned earlier, earlier Enermax models had a linear thermal controller that spun up the fan unnecessarily even when not needed. The NoiseTaker shows more sophistication. From the manual comes this description and graph:

"RPM of 8cm & 9cm fans can be manually adjustable (sic) from low to high rpm level according to user°s need to keep the balance between acoustic noise and cooling effect. In addition, we also feature thermal control circuit to NoiseTaker series power supply to regulate both 8cm and 9cm fans to adjust to various system loading conditions and provide necessary cooling. 8cm fan rpm can be monitored by BIOS or software through the output of tachometer signal."

As with most manual fan speed controllers, this one is tied to a thermistor that determines both the minimum and maximum speed available. With the PSU at 40% load or less, the range is from 27% to 60% of maximum fan speed; at 100% load, the range is 84% to 100% of max fan speed.

Note that the term SYSTEM LOADING in the graph is rather vague. The graph suggests that the fan controller somehow varies fan speed in accordance with system load; it does not. As with all automatic fan speed PSUs on the market, the fan speed is tied to the temperature seen by a thermistor (a resistor whose value varies with temperature) inside the PSU. Certainly, temperature is affected by system load, but there is no direct controlling relationship between system load and PSU fan speed.

The presence of the long plateau on the left side of the graph is a good sign. It means that the NoiseBlocker's fan stays at minimum speed up to some preset temperature, and speeds up only beyond this point. It is the basic approach taken by almost all the PSUs that strive for lower noise: The fan speed is increased on when it is really needed to keep temperatures inside the PSU in a safe zone.

VISUAL ANALYSIS

In the photo on the previous page, you've seen what you'd see once the NoiseTaker is installed in your PC. How about a look at the retail box? It has changed. It is about the largest PSU box I've seen yet. Nice graphics, lots of techno marketing to peruse. A power cord, 4 mounting screws, some Enermax stickers and a manual are provided.

The inside end of the PSU sports the thickest hose-like cabling I've ever seen in a PSU. They are all so stiff that routing them in a PC will be a pain for most people. It appears to be the insulation braiding or plastic wrap around the wires that's responsible for the stiffness, not the wires themselves. The intake vents are nicely open and generous, covering at least 2/3s of the panel. There are not other vent holes, other than the usual 92mm Enermax intake fan bottom panel. (The PSU is shown upside down so you can see the fan.)

The cables are shorter than seen on previous Enermax models. In some large cases, they might be a bit short, especially when combined with the stiffness. There are three wire bundles:

  • 20" long cable for main 20-pin ATX connector, stiff silver braided insulation almost the entire length.
  • 20" long bundle of dual 12V connector cable, cable with 4-pin connector marked EXTRA, and AUX connector cable, stiff silver braiding along half the length.
  • Peripheral bundle with -

    - 27" cable w/dual SATA connectors

    -
    27" cable w/4-pin connector and floppy drive connector

    - 20" cable w/4-pin connector and floppy drive connector

    - 20" cable w/three 4-pin connectors


    - 28" fan RPM cable for motherboard

On the inside, the heatsinks look surprisingly small, given the power rating. Ditto the main capacitors on the left.

The wiring bundles make for a very tight fit on one side. Small connectors are used for both fans, but they are so hard to get at that I could only hook up voltage monitors for the 92mm fan (in preparation for the testing). It's not clear whether both fans get the same voltage.

The fans are labeled "SILENCE". They are 12VDC ball bearing models. The 80mm fan is rated for 0.17A, which makes it a medium speed fan, and the 92mm fan is rated at 0.27A, which is fairly typical for a high speed fan.

TEST RESULTS

For a complete rundown of testing equipment and procedures, please refer to the article SPCR's Revised PSU Testing System.

FUNCTION TOOL
Measure temperature of ambient air, case, and PSU exhaust
Digital readout thermometer. There are several in the lab that are used. (Like DigiDoc.) They measure within ~1°C of each other, which is good enough for our purposes. Powered by the PSU being tested. (1~2W power draw.)
Measure voltages across fans and DC output line
Heath / Zenith SM-2320 multimeter. This is an ordinary multimeter. It has been compared against a much more expensive lab instrument and comes very close (within 2%) on readings of 0~20VDC.
Load PSU to specific DC output power loads for each voltage line

Click for larger imageDBS-2100 PSU load tester. Made specifically for testing computer power supplies, it consists of a large bank of high power precision resistors along with an extensive selection of switches on the front panel calibrated in Amps (current) and grouped into 6 voltage lines: +5, +12, -12V, +3.3, -5, +5SR. Leads from the PSU plug into the front panel, and there are taps for taking voltage readings for the 3.3V, 5V and 12V lines.

Measure AC power, power factor (PF), VA, AC line voltage
Kill-A-Watt Power Meter. An inexpensive consumer power meter with very good accuracy and a host of useful functions.

Measure noise in dBA from 1 meter distance B&K model 2204 sound level meter. This professional caliber SLM dates back to 1978, weighs over 10 pounds, and is completely analog in design. It has a dynamic range that spans over 140 dB. The unit's absolute sensitivity reaches below 0 dBA. A quiet environment is a prerequisite to low noise testing; the lab has been measured down to ~17 dBA at night, and a 12 dBA adjacent room is also available for any PSUs that are quieter.

Thermal environment directly related to the power delivered. Custom Thermal Simulation Box. A NEW ADDITION to the lab, it ensures that the heat generated by the PSU creates the thermal ambient of its working environment. Please see SPCR's Revised PSU Testing System for full details!

The testing was conducted in the main lab, a converted 10' x 10' kitchen with a ceiling about 8.5' high. It's a room that's bare except for electronics, PC gear and instruments with a tiled linoleum floor. Acoustics are lively and reflective. Ambient during testing: 22°C and 17 dBA.

An Important Note about the new thermal simulation box is that it has NO exhaust ventilation other than the PSU fans. The box is not perfectly sealed, and around the hole where the cables exit, a fair amount of air can be felt blowing out. Normal PC cases have at least one or two ventilation fans other than the PSU fan. It probably means that the simulation is tougher than real systems in some ways.

On the other hand, the heat in a system is concentrated very close to the PSU -- both the CPU and the VGA card, which together can generate nearly well over 150W of heat, are situated directly beneath the PSU in a mid tower. In my thermal simulation box, the heat source is much farther away, and there are four 0.25A 80mm fans flowing cool air across the hot resistors. Of course, the heated air exhaust from the hot resistors is what fills the box, so perhaps its six of one or half a dozen of the other for either argument.

For the record, here's a photo of the Enermax NoiseTaker 475 in the PSU test rig. The unit had to be held down with masking tape to make sure the tension of the ATX cable would not pull it out. That cable was stretched as far as it could go.

Enermax NoiseTaker 475
DC Output (W)
65
90
150
200
250
300
400
470
AC Input (W)
85
118
189
247
308
364
500
595
Efficiency
76%
76%
79%
81%
81%
82%
80%
79%
Case Temp (°C)
27
27
29
31
34
35
37
39
PSU Exhaust (°C)
28
28
30
32
37
39
40
44
Fan Voltage (min/max)
3.0/6.0
3.0/6.0
3.0/6.6
3.1/6.8
5.8/10.5
7.5/11.5
11.5/11.5
11.5/11.5
Noise, min (dBA/1m)
21
21
21
21
32
35
44
44

1. VOLTAGE REGULATION is very good, within -/+2% on all lines in any nominal combination of loads. The low and high voltage seen on each of the main lines is shown:

  • +12V: 11.8 to 12.3
  • +5V: 4.8 to 5.3
  • +3.3V: 3.3 to 3.5

We have no way of testing line regulation; AC conditions are steady-state, not dynamic as it would be (potentially) in a real PC. The AC line in the test lab as measured by Kill-a-Watt is usually very stable, within a couple of volts of 120V.

2. EFFICIENCY is the highest of any PSU tested by SPCR so far. No other unit has ever reached 80% in the SPCR lab. The Enermax NoiseTaker 475 actually hit 82%! The closest runner-ups are the Seasonic Super series PSUs, which reach 78-79% at max efficiency. This performance is all the more amazing when you consider that neither the Enermax spec sheet nor their promotional marketing materials even mentions efficiency.

In fact, the efficiency is so high that after the first run of tests, I ran them all through again, sure that I had made an error -- and got the same results. The small difference between case and exhaust temperatures is one practical indication of this efficiency: The PSU adds little additional heat to the air going through it under all but the highest loads.

3. POWER OUTPUT: The unit had no trouble at all in the test environment, and ran with great stability at all the lower output levels. Even at 400W output, it ran for a full 5 minutes without any sign of overheating or overload.

After about 3.5 minutes at 470W, however, protection circuitry kicked in and the unit simply shut down. The fans stayed running at least 3 mninutes after the PSU had shut down, as advertised. In this case, this feature seemed like a good thing. After the fans stopped, I reduced the load and turned the power switch off and on. It came right back on without any problems, and no apparent damage.

It is not clear why the unit shut down. There are several protective features that can shut this PSU down:

  • Over Voltage Protection - unlikely; none of the output voltages were misbehaving
  • Over Load Protection - unlikely; the load was exactly at maximum
  • Over Current Protection - maybe: very clear limits are specified, and in setting the load for 470W, I may have exceeded the limit on one of the voltage lines.
  • Over Temperature Protection - possible: 40°C is the specified maximum operating temperature, and the case temperature was recorded at 39°C, with exhaust at 44°C. How one defines or where one measures the temperature becomes very difficult. If the Over Temperature Protection function shut the unit down, it is very probable that the operating temperature (as Enermax defines it) was exceeded. As it is so unlikely for any system to reach steady 470W output for any length of time, never mind 3.5 minutes, I have no quibble with the shutdown. It is a very extreme and unrealistic test. In fact, I am pleased that the protection circuitry worked well.

4. POWER FACTOR is as expected for a passive or non-PFC unit (not specified in the specs), staying at around 0.65 throughout the testing. An Active PFC version appears to be available or at least in the works, according to the Enermax web site.

5. FAN VOLTAGE: As noted earlier, only the 92mm fan voltage was monitored. It is not certain whether the 80mm fan receives the same voltage. The 92mm fan gets full voltage (11.5V) for a couple of seconds upon startup to ensure that it always starts. The default voltage just after a cool start is ~3V. In the thermal simulation case, the first significant change comes at the 250W output level. The fan voltage jumps from 3.1V at 200W to 5.8V at 250W. At 400W and up, the fan voltage is pegged at 11.5V. Upon shutdown, the fans continue blowing at minimum or a bit higher (depending on temperature when shut down) for at least 2 minutes.

6. NOISE was measured at 1 meter from the exhaust grill with the manual fan speed knob always at minimum. The test environment is live, so readings may be higher than would be obtained in an anechoic chamber.

Subjectively, the Enermax NoiseTaker 475 is very quiet from idle all the to 200W output: There was no change in noise from 65W load to 200W. But between 200W and 250W output, there is a major step in fan speed and noise, and hits 32dBA at 250W. All the noise levels at the 250W mark and beyond are too high to be of real interest to PC Silencers.

The quality of the fan noise is not particularly smooth, however. Even at the lowest speed, there is a kind of rattling-chugging sound. This noise actually dissipates as the fans spin up, and at higher speeds, the whooshing of fan turbulence dominates. There are no high frequency sounds that can be detected, not from the fans or from the electronics. Coil noise is often the result of interactions between components, however, so the absence of this noise in the lab does not guarantee its absence with PC components.

The minimum noise is not better than the quietest PSUs tested, especially when the quality of the noise is considered, but the ramp-up step of fan speed at over ~200W output is at considerably a higher point than seen before. This may give the Enermax NoiseTaker a very practical real-world advantage when used in high power systems.

A CAUTION: The noise-to-power performance achieved here is specific to prevailing temperatures. In other words, if your ambient temperature is 35°C and your case temperature measures 40°C, you can expect much higher noise, regardless of the electrical load. Similar, in fact, to that obtained here at 400W and above: Loud.

CONCLUSION

The Enermax NoiseTaker 475 frankly surprised me. I was not expecting anything special from this model, jaded as I am with marketing hokum from any source; Enermax spreads its share of such hokum. I certainly was not expecting 82% maximum efficiency, nor low-noise operation to 200W and beyond. Both of these qualities are enough to immediately put this model among the Recommended PSUs. Add the high stability and high power capability, and it really starts to look like... something special?

It's true that the ATX12V V1.3 PSU Guideline calls for higher efficiency than before, but the numbers ° 70% at full load, 60% at typical load and 50% at light load ° are nowhere near what Enermax has achieved here.

The protection circuitry works well. In truth, it would be amazingly difficult to build a desktop system that could demand 470W from the PSU for any length of time. Thus far, the highest power draw I've seen is with an ARM Systems P4-3.2 dual SATA drive PC, which only demanded 235W max in AC power. This NoiseTaker was drawing 600W in AC voltage before the protection circuits shut it down.

This is not to say the unit has no flaws.

The bunched cables may be tidy and nice looking but ye gads, get those girdles off! They could be a real struggle to manage in a real system. Even Ralf Hutter's cabling skills may not be enough here.

Then there are the fans that clatter at low speed; they really can and should be improved. Yes, the usual swaps with quieter fans will make real improvements here, if you can negotiate the tangle of wires inside and are willing to void that 3-year warranty. (The full voltage startup surge should help most fan get started and 3V may be be enough to keep most of them running once they're started).

Sorry to be addressing just the modders and diehards.

Even without any modifications, the Enermax NoiseTaker 475 will be useful and important for people who want to build high power systems that still run quietly. It may not be the quietest PSU at idle, but at 200W output and still just in the low-20s dBA @ 1 meter, it is tough to beat!

It would certainly be interesting to look at the other models in the NoiseTaker line. If that >200W fan speed ramp up point remains unchanged, the lower power NoiseTakermodels would be of great interest to SPCR enthusiasts.

Much thanks to Maxpoint for the Enermax NoiseTaker 475 review sample and for their kind support.

* * *

POSTSCRIPT: Tests Repeated after Changes to PSU Test Platform! See Page 4!

POSTSCRIPT: Tests Repeated after Changes to PSU Test Platform

Further examination of the new PSU Test Platform, and consideration of readers' feedback resulted in two changes to the Thermal Simulation Box:

  • The addition of a low airflow 80mm exhaust fan on the "back panel" beneath the PSU.
  • The four 80mm fans that move the heat from the Load Tester to the Thermal Simulation box are now set to run at 5V rather than 12V.

The end result should be a terst platform that more closely resembles quiet low airflow PC mid-tower. Please read the Postscript in the New PSU Test Platform article for full details.

In the meanwhile the Enermax NoiseTaker 475 was tested all over again with the changed test rig. As before, ambient conditions during testing were 22°C and 17 dBA.

Enermax NoiseTaker 475
DC Output (W)
65
90
150
200
250
300
400
470
Case Temp (°C)
27
27
29
31
34
35
37
39
PSU Exhaust (°C)
28
28
30
32
37
39
40
44
Fan Voltage (min/max)
3.0/6.0
3.0/6.0
3.0/6.6
3.1/6.8
5.8/10.5
7.5/11.5
11.5/11.5
11.5/11.5
Noise, min (dBA/1m)
21
21
21
21
32
35
44
44
°
Case Temp (°C)
27
27
30
34
35
35
37
39
PSU Exhaust (°C)
28
28
31
36
38
39
40
44
Fan Voltage (min/max)
3.0/6.0
3.0/6.0
3.1/6.6
3.8/7.1
5.9/10.7
7.5/11.5
11.5/11.5
11.5/11.5
Noise, min (dBA/1m)
21
21
21
24
32
35
44
44

The data in the light green is from the previous test. The data in yellow is the new test results after the changes. It's interesting to note that neither the higher or lower power levels were affected by the change. It is the greyed out 150~250W middle range that is most affected.

1. Comparing the 150W power levels, the new Test Rig configuration is getting a bit hotter a bit sooner, but we're only just beginning to see the difference here.

2. At the 200W level, the difference is more marked. Temperatures for both case and exhaust are 3~4°C higher in the new Test Rig config, fan voltages significantly higher, and the noise audibly higher.

3. At 250W, the thermals are only marginally higher in the new Test Rig config, and beyond that, there is no change.

The fan ramp-up transition phase begins earlier and is more stretched out that with the previous test config. It is not a big change, but one that will make it a bit tougher for PSUs to stay cool and quiet to higher output levels.

Apologies for any confusion...

* * *

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