Enermax ECO80+ 620 W Power Supply Review
By Gabriel Torres on July 9, 2009


Introduction

Hardware Secrets Golden Award

Enermax ECO80+ 620 W (EES620AWT) features a magnetic bearing fan with batwing blades for ultra low noise – design that is being called “twister bearing” by the manufacturer – and promises up to 86% efficiency. Let’s see if it is really a good product.

The reviewed power supply is officially a 620 W power supply labeled at 40° C (which is great), and the product box says that it can handle up to 680 W peak. This is really nice to see, because some manufacturers would do the opposite, i.e., label the power supply with its peak power and then put in small letters on the box the real capacity with the word “continuous” after it. Kudos to Enermax.

Enermax ECO 80+ 620 W power supply
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Figure 1: Enermax ECO80+ 620 W power supply.

Enermax ECO 80+ 620 W power supply
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Figure 2: Enermax ECO80+ 620 W power supply.

ECO80+ power supplies do not have a modular cabling system like the Liberty ECO series from the same manufacturer. This allowed the reviewed unit to be very small, being only 5 ½” (140 mm) deep.

As mentioned it comes with this “twister bearing” fan on its bottom, which is a magnetic bearing fan with batwing blades. This bearing has a higher life-span and reduces noise a little bit (1-2 dBA), while the shape of the blades improves airflow by 20-30% and also helps reducing noise. The rounded shape of the air inlet, called AirGuard by Enermax, helps reducing noise as well.

Enermax ECO 80+ 620 W power supply
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Figure 3: The “twister bearing” fan.

All cables have a nylon protection that comes from inside the power supply. The included cables are:

The number of cables is enough for you to build a mainstream PC.

All wires are 18 AWG, which is the correct gauge to be used. All cables are long, measuring 22 3/64” (56 cm) between the power supply and the first connector on the cable, but then only 4” (10 cm) between each connector on the cable on cables that have more than one connector. We think that Enermax could give more space between the connectors.

Enermax ECO 80+ 620 W power supply
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Figure 4: Cables.

Now let’s take an in-depth look inside this power supply.

A Look Inside The ECO80+ 620 W

We decided to disassemble this power supply to see what it looks like inside, how it is designed, and what components are used. Please read our Anatomy of Switching Power Supplies tutorial to understand how a power supply works and to compare this power supply to others.

This page will be an overview, and then in the following pages we will discuss in detail the quality and ratings of the components used.

Here we could see that the printed circuit board used on ECO80+ 620 W is exactly the same used by Enermax PRO82+ and MODU82+ series. On a closer look we could see that internally ECO80+ 620 W is identical to Liberty ECO 620 W but without the modular cabling system.

Enermax ECO 80+ 620 W power supply
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Figure 5: Overall look.

Enermax ECO 80+ 620 W power supply
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Figure 6: Overall look.

Enermax ECO 80+ 620 W power supply
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Figure 7: Overall look.

Transient Filtering Stage

As we have mentioned in other articles and reviews, the first place we look when opening a power supply for a hint about its quality, is its filtering stage. The recommended components for this stage are two ferrite coils, two ceramic capacitors (Y capacitors, usually blue), one metalized polyester capacitor (X capacitor), and one MOV (Metal-Oxide Varistor). Very low-end power supplies use fewer components, usually removing the MOV and the first coil.

The transient filtering stage from this power supply is flawless, providing two Y capacitors and one ferrite coil more than required, plus one X capacitor after the rectifying bridge. The MOV is located after the bridge and not before as usual.

Enermax ECO 80+ 620 W power supply
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Figure 8: Transient filtering stage (part 1).

Enermax ECO 80+ 620 W power supply
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Figure 9: Transient filtering stage (part 2).

In the next page we will have a more detailed discussion about the components used in the Enermax ECO80+ 620 W.

Primary Analysis

On this page we will take an in-depth look at the primary stage of Enermax ECO80+ 620 W. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.

This power supply uses one GBU15J rectifying bridge in its primary, which can deliver up to 15 A at 100° C. This component is clearly overspec’ed: at 115 V this unit would be able to pull up to 1,725 W from the power grid; assuming 80% efficiency, the bridge would allow this unit to deliver up to 1,380 W without burning this component. Of course we are only talking about this component and the real limit will depend on all other components from the power supply.

Enermax ECO 80+ 620 W power supply
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Figure 10: Rectifying bridge.

On the active PFC circuit two IRFP460A power MOSFET transistors are used, each one capable of delivering up to 20 A at 25° C or 13 A at 100° C in continuous mode (note the difference temperature makes), or up to 80 A in pulse mode at 25° C. These transistors present a resistance of 270 mΩ when turned on, a characteristic called RDS(on). This number indicates the amount of power that is wasted, so the lower this number the better, as less power will be wasted thus increasing efficiency.

This power supply uses two electrolytic capacitors to filter the output from the active PFC circuit. The use of more than one capacitor here has absolute nothing to do with the “quality” of the power supply, as laypersons may assume (including people without the proper background in electronics doing power supply reviews around the web). Instead of using one big capacitor, manufacturers may choose to use two or more smaller components that will give the same total capacitance, in order to better accommodate space on the printed circuit board, as two or more capacitors with small capacitance are physically smaller than one capacitor with the same total capacitance. On ECO80+ 620 W two 220 µF x 400 V capacitors are used in parallel; this is equivalent of one 440 µF x 400 V capacitor.

These capacitors are Japanese, from Chemi-Con and are labeled at 85° C.

In the switching section, another two IRFP460A power MOSFET transistors are used on the traditional two-transistor forward configuration.

Enermax ECO 80+ 620 W power supply
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Figure 11: Active PFC transistor, active PFC diode, switching transistor and standby (+5VSB) switching transistor.

The primary is controlled by a CM6802 PFC/PWM combo controller, which is an updated version from the famous CM6800 controller.

Enermax ECO 80+ 620 W power supply
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Figure 12: PFC/PWM combo controller.

Now let’s take a look at the secondary of this power supply.

Secondary Analysis

This power supply uses four Schottky rectifiers on its secondary.

The maximum theoretical current each line can deliver is given by the formula I / (1 - D), where D is the duty cycle used and I is the maximum current supported by the rectifying diode. Just as an exercise, we can assume a typical duty cycle of 30%.

The +12 V output is produced by two SBR40U60PT (40 A, 15 A per internal diode at 25° C, maximum voltage drop of 0.60 V) connected in parallel. This gives us a maximum theoretical current of 57 A or 686 W for the +12 V output.

By the way, we are now talking about the voltage drop presented by the rectifiers. This parameter shows how much voltage is wasted by the rectifier. The lower this number is, the better, as less voltage is wasted, increasing efficiency.

The +5 V output is produced by one DF40SC4 Schottky rectifier (40 A, 20 A per internal diode at 106° C, maximum voltage drop of 0.55 V), giving us a maximum theoretical current of 29 A or 143 W for this output.

The +3.3 V output is produced by one DF30SC4 Schottky rectifier (30 A, 15 A per internal diode at 112° C, maximum voltage drop of 0.55 V), giving us a maximum theoretical current of 21 A or 71 W for this output.

All these numbers are theoretical. The real amount of current/power each output can deliver is limited by other components, especially by the coils used on each output.

Enermax ECO 80+ 620 W power supply
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Figure 13: Rectifiers.

The outputs are monitored by a PS223 integrated circuit, which supports under voltage (UVP), over voltage (OVP), over current (OCP) and over temperature (OTP) protections. Any other protection that this unit may have is implemented outside this integrated circuit.

Enermax ECO 80+ 620 W power supply
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Figure 14: Monitoring integrated circuit.

Most electrolytic capacitors from the secondary are from CEC, a Hong Kong-based company.

Power Distribution

In Figure 15, you can see the power supply label containing all the power specs.

Enermax ECO 80+ 620 W power supply
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Figure 15: Power supply label.

This power supply has two +12 V rails distributed like this:

This is a distribution a little bit different than usual.

Now let’s see if this power supply can really deliver 620 W.

Load Tests

We conducted several tests with this power supply, as described in the article Hardware Secrets Power Supply Test Methodology.

First we tested this power supply with five different load patterns, trying to pull around 20%, 40%, 60%, 80%, and 100% of its labeled maximum capacity (actual percentage used listed under “% Max Load”), watching how the reviewed unit behaved under each load. In the table below we list the load patterns we used and the results for each load.

If you add all the power listed for each test, you may find a different value than what is posted under “Total” below. Since each output can vary slightly (e.g., the +5 V output working at +5.10 V), the actual total amount of power being delivered is slightly different than the calculated value. On the “Total” row we are using the real amount of power being delivered, as measured by our load tester.

+12V1 and +12V2 are the two independent +12V inputs from our load tester and during our tests the +12V1 input was connected to the +12V1 (main motherboard connector) and +12V2 (video card and peripheral power connectors) rails, while the +12V2 input was connected to the +12V1 (EPS12V connector) rail.

Input

Test 1

Test 2

Test 3

Test 4

Test 5

+12V1

5 A (60 W)

9 A (108 W)

14 A (168 W)

19 A (228 W)

24 A (288 W)

+12V2

4 A (48 W)

9 A (108 W)

14 A (168 W)

18 A (216 W)

23 A (276 W)

+5V

1 A (5 W)

2 A (10 W)

4 A (20 W)

5 A (25 W)

6 A (30 W)

+3.3 V

1 A (3.3 W)

2 A (6.6 W)

4 A (13.2 W)

5 A (16.5 W)

6 A (19.8 W)

+5VSB

1 A (5 W)

1 A (5 W)

1.5 A (7.5 W)

2 A (10 W)

2.5 A (12.5 W)

-12 V

0.5 A (6 W)

0.5 A (6 W)

0.5 A (6 W)

0.5 A (6 W)

0.5 A (6 W)

Total

130.5 W

249.2 W

389.7 W

509.4 W

638.7 W

% Max Load

21.0%

40.2%

62.9%

82.2%

103.0%

Room Temp.

45.9° C

45.7° C

49.6° C

46.2° C

46.5° C

PSU Temp.

48.2° C

46.9° C

50.6° C

52.3° C

53.0° C

Voltage Stability

Pass

Pass

Pass

Pass

Pass

Ripple and Noise

Pass

Pass

Pass

Pass

Pass

AC Power

155.5 W

292.3 W

462.7 W

617.0 W

797.0 W

Efficiency

83.9%

85.3%

84.2%

82.6%

80.1%

AC Voltage

113.3 V

111.8 V

109.4 V

107.7 V

104.1 V

Power Factor

0.957

0.972

0.982

0.987

0.990

Final Result

Pass

Pass

Pass

Pass

Pass

Enermax ECO80+ 620 W presents high efficiency between 84% and 85% if you pull up to 60% from its labeled capacity, i.e., up to 372 W. At 80% load (496 W) efficiency dropped to 82.6%, still a good number. At full load (620 W) efficiency dropped to 80%.

Voltage stability is another highlight from this product. All voltages (including -12 V) were within 3% from their nominal value, whereas the ATX specification says they must be within 5%. Translation: voltages were closer to their nominal values than needed.

Ripple and noise were extremely low. You can see the results for test number five below. All numbers are peak-to-peak figures and the maximum allowed is 120 mV for the +12 V outputs and 50 mV for the +3.3 V and +5 V outputs.

Enermax ECO 80+ 620 W power supply
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Figure 16: +12V1 input from load tester at 638.7 (45.4 mV).

Enermax ECO 80+ 620 W power supply
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Figure 17: +12V2 input from load tester at 638.7 (45.0 mV).

Enermax ECO 80+ 620 W power supply
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Figure 18: +5V rail with power supply delivering 638.7 (14.2 mV).

Enermax ECO 80+ 620 W power supply
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Figure 19: +3.3 V rail with power supply delivering 638.7 (11.4 mV).

Let’s see if we could pull more than 620 W from this unit.

Overload Tests

Before overloading a power supply we always test to see if over current protection (OCP) is active and at what current level it is triggered. To test this we installed only the main motherboard connector and the EPS12V connector to the load tester +12V1 input, since these two connectors were installed on the power supply +12V1 rail. OCP entered in action when we tried pulling 33 A or more from the power supply +12V1 rail.

Then starting from test five we increased currents to the maximum we could with the power supply still running inside ATX specs. The results are below. If we tried to increase one amp more on any output ripple would  jump to the roof, showing that we had already reach the maximum this unit could deliver.

The idea behind of overload tests is to see if the power supply will burn/explode and see if the protections from the power supply are working correctly. This power supply didn’t burn and when we tried to pull far more than it could deliver it would shut down, so this unit passed on this test.

As you can see Enermax could have labeled this unit as a 750 W product, but they decided not to do so probably because of efficiency, which drops below 80% if we pull more than 620 W from it.

Input

Maximum

+12V1

28 A (336 W)

+12V2

28 A (336 W)

+5V

10 A (50 W)

+3.3 V

10 A (33 W)

+5VSB

3 A (15 W)

-12 V

0.5 A (6 W)

Total

778.4 W

% Max Load

125.5%

Room Temp.

46.5° C

PSU Temp.

53.0° C

AC Power

1,007 W

Efficiency

77.3%

AC Voltage

104.8 V

Power Factor

0.993

Main Specifications

Enermax ECO80+ 620 W power supply specs include:

* Researched at Newegg.com on the day we published this review.

 

Conclusions

Enermax ECO80+ 620 W is identical to Enermax Liberty ECO 620 W but without the modular cabling system and with the quiet magnetic fan with batwing blades, with the great advantage of being USD 20-40 cheaper.

If you are building a mainstream PC, Enermax ECO80+ 620 W won’t let you down: typical efficiency of 85%, extremely stable voltages and very low ripple and noise levels.

If you plan to build an SLI or CrossFire system with two high-end video cards you will have to look for a different product, as ECO80+ 620 W only provides two video card power connectors and each high-end video card requires two of them.

Originally at http://www.hardwaresecrets.com/article/Enermax-ECO80+-620-W-Power-Supply-Review/755


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