LEPA G850-MAS Power Supply Review
By Gabriel Torres on August 9, 2012


Introduction

Hardware Secrets Golden Award

The LEPA already had a power supply series called “G,” with 500 W, 700 W, and 900 W models. We reviewed the 500 W and 700 W models, and they deserved our recommendation. Now LEPA is releasing 650 W, 750 W, and 850 W models within its “G” series, but those models are manufactured by a different company. Let’s see how the new 850 W model fared in our tests.

The new 650 W, 750 W, and 850 W models are manufactured by CWT, while the 500 W, 700 W, and 900 W models are manufactured by Enermax. The LEPA G850-MAS is a rebranded CWT PUQ(G)-850 (a.k.a. PUQ750V-G) power supply.

LEPA G850-MAS
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Figure 1: LEPA G850-MAS power supply

LEPA G850-MAS
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Figure 2: LEPA G850-MAS power supply

The LEPA G850-MAS is 6.3” (160 mm) deep, using a 140 mm ball-bearing fan on its bottom (Yate Loon D14BH-12).

LEPA G850-MAS
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Figure 3: Fan

The reviewed power supply has a modular cabling system with six connectors: two for video cards and four for SATA or peripheral power connectors. The main motherboard cable and the ATX12V/EPS12V cables are permanently attached to the power supply. These cables are protected with nylon sleeves, which come from inside the unit. This power supply comes with the following cables:

All wires are 18 AWG, which is the minimum recommended gauge, except the main motherboard cable, which uses thicker 16 AWG wires. The number of connectors is adequate for an 850 W power supply, however, we’d prefer that this power supply would come with six video card power connectors, which would allow for out-of-the-box support for three high-end video cards.

LEPA G850-MAS
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Figure 4: Cables

Let’s now take an in-depth look inside this power supply.

A Look Inside the LEPA G850-MAS

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.

On this page we will have an overall look, and then in the following pages we will discuss in detail the quality and ratings of the components used.

LEPA G850-MAS
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Figure 5: Top view

LEPA G850-MAS
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Figure 6: Front quarter view

LEPA G850-MAS
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Figure 7: Rear quarter view

LEPA G850-MAS
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Figure 8: The printed circuit board

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. 

In the transient filtering stage, this power supply is flawless, with two Y capacitors and one X capacitor more than the minimum required.

LEPA G850-MAS
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Figure 9: Transient filtering stage (part 1)

LEPA G850-MAS
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Figure 10: Transient filtering stage (part 2)

On the next page, we will have a more detailed discussion about the components used in the LEPA G850-MAS.

Primary Analysis

On this page we will take an in-depth look at the primary stage of the LEPA G850-MAS. For a better understanding, please read our “Anatomy of Switching Power Supplies” tutorial.

This power supply uses two GBU806 rectifying bridges connected in parallel and attached to an individual heatsink. Each bridge supports up to 8 A at 100° C. So, in theory, you would be able to pull up to 1,840 W from a 115 V power grid. Assuming 80% efficiency, these bridges would allow this unit to deliver up to 1,472 W without burning themselves out (up to 1,656 W at 90% efficiency). Of course, we are only talking about these particular components. The real limit will depend on all the components combined in this power supply.

LEPA G850-MAS
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Figure 11: Rectifying bridges

The active PFC circuit uses two IPW60R190E6 MOSFETs, each supporting up to 20.2 A at 25° C or 12.8 A at 100° C in continuous mode (see the difference temperature makes) or 59 A at 25° C in pulse mode. These transistors present a maximum 190 mΩ resistance when turned on, a characteristic called RDS(on). The lower the number the better, meaning that the transistor will waste less power, and the power supply will have a higher efficiency.

LEPA G850-MAS
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Figure 12: Active PFC transistors

The output of the active PFC circuit is filtered by one 470 µF x 400 V Japanese electrolytic capacitor, from Panasonic, labeled at 105° C.

LEPA G850-MAS
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Figure 13: Capacitor

In the switching section, two IPW60R099C6 MOSFETs are employed using the traditional two-transistor forward configuration. Each transistor supports up to 37.9 A at 25° C or 24 A at 100° C in continuous mode or 112 A at 25° C in pulse mode, with a maximum RDS(on) of 99 mΩ.

LEPA G850-MAS
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Figure 14: Switching transistors

The switching transistors are managed by a CM6802 active PFC/PWM combo controller.

LEPA G850-MAS
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Figure 15: Active PFC/PWM controller

Let’s now take a look at the secondary of this power supply.

Secondary Analysis

The LEPA G850-MAS uses a synchronous design, meaning that the rectifiers were replaced with MOSFETs. Also, this power supply uses a DC-DC design, meaning that it is basically a +12 V power supply, with the +5 V and +3.3 V outputs being generated through two smaller switching power supplies connected to the +12 V rail. Both designs are used to increase efficiency.

The +12 V output uses five IPD031N06L3 G MOSFETs, each supporting up to 100 A at 100° C in continuous mode or up to 400 A at 25° C in pulse mode, with a maximum RDS(on) of 3.1 mΩ. These transistors are controlled by an SP6019 integrated circuit, and they are located on a small daughterboard.

LEPA G850-MAS
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Figure 16: The +12 V transistors

The DC-DC converters are located on the same printed circuit board as the modular cabling system. Both are managed by an APW7159 PWM controller, with each output using a pair of AP72T03GH MOSFETs, each supporting up to 63 A at 25° C or 44 A at 100° C in continuous mode or up to 190 A at 25° C in pulse mode, with a maximum RDS(on) of 9 mΩ.

LEPA G850-MAS
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Figure 17: The DC-DC converters

LEPA G850-MAS
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Figure 18: The DC-DC converters

The outputs of this power supply are monitored by a WT7502 integrated circuit, which only supports over voltage (OVP) and under voltage (UVP) protections.

LEPA G850-MAS
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Figure 19: Monitoring circuit

This power supply uses a mix of Japanese electrolytic capacitors, from Chemi-Con, and solid capacitors to filter its outputs. See Figure 20.

LEPA G850-MAS
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Figure 20: Capacitors

Power Distribution

In Figure 21, you can see the power supply label containing all the power specs.

LEPA G850-MAS
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Figure 21: Power supply label

As you can see, this power supply has a single +12 V rail, so there is not much to talk about here.

How much power can this unit really deliver? Let’s find out.

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 the behavior of the reviewed unit 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 powers listed for each test, you may find a different value than what is posted under “Total” below. Since each output can have a slight variation (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. In the “Total” row, we are using the real amount of power being delivered, as measured by our load tester.

The +12VA and +12VB inputs listed below are the two +12 V independent inputs from our load tester. During this test, both inputs were connected to the power supply’s single +12 V rail. (The power supply’s EPS12V connector was installed on the +12VB input of the load tester.)

Input

Test 1

Test 2

Test 3

Test 4

Test 5

+12VA

6 A (72 W)

13 A (156 W)

19 A (228 W)

25.5 A (306 W)

32 A (384 W)

+12VB

6 A (72 W)

13 A (156 W)

19 A (228 W)

25.5 A (306 W)

31.5 A (378 W)

+5 V

1 A (5 W)

2 A (10 W)

4 A (20 W)

6 A (30 W)

8 A (40 W)

+3.3 V

1 A (3.3 W)

2 A (6.6 W)

4 A (13.2 W)

6 A (19.8 W)

8 A (26.4 W)

+5VSB

1 A (5 W)

1.5 A (7.5 W)

2 A (10 W)

2.5 A (12.5 W)

3 A (15 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

165.4 W

345.6 W

508.6 W

681.4 W

848.4 W

% Max Load

19.5%

40.7%

59.8%

80.2%

99.8%

Room Temp.

45.0° C

45.5° C

46.9° C

49.4° C

49.0° C

PSU Temp.

48.4° C

48.6° C

49.2° C

50.6° C

52.3° C

Voltage Regulation

Pass

Pass

Pass

Pass

Pass

Ripple and Noise

Pass

Pass

Pass

Pass

Pass

AC Power

187.5 W

382.9 W

570.1 W

777.0 W

990.0 W

Efficiency

88.2%

90.3%

89.2%

87.7%

85.7%

AC Voltage

114.6 V

112.4 V

110.6 V

107.9 V

104.6 V

Power Factor

0.961

0.982

0.991

0.994

0.996

Final Result

Pass

Pass

Pass

Pass

Pass

The 80 Plus Gold certification promises a minimum efficiency of 90% at typical load (i.e., 50% load) and a minimum efficiency of 87% at light (i.e., 20% load) and full loads. The LEPA G850-MAS presented efficiency between 85.7% and 90.3% during our tests. At the full load test, efficiency was below 87%, which can be explained by the AC voltage at our lab that dropped to 104.6 V, and power supplies present lower efficiency at lower AC voltages. Therefore, we can claim the LEPA G850-MAS passed our efficiency tests.

All positive voltages were closer to their nominal values during all tests (3% voltage regulation). The -12 V output was outside this tighter range during tests one through four, but still inside the allowed range. The ATX12V specification states that positive voltages must be within 5% of their nominal values, and negative voltages must be within 10% of their nominal values.

Let’s discuss the ripple and noise levels on the next page.

Ripple and Noise Tests

Voltages at the power supply outputs must be as “clean” as possible, with no noise or oscillation (also known as “ripple”). The maximum ripple and noise levels allowed are 120 mV for +12 V and -12 V outputs, and 50 mV for +5 V, +3.3 V and +5VSB outputs. All values are peak-to-peak figures. We consider a power supply as being top-notch if it can produce half or less of the maximum allowed ripple and noise levels.

The LEPA G850-MAS provided low ripple and noise levels, making it a “flawless” unit here.

Input

Test 1

Test 2

Test 3

Test 4

Test 5

+12VA

14.2 mV

20.0 mV

28.4 mV

39.4 mV

50.4 mV

+12VB

12.6 mV

17.4 mV

26.8 mV

39.4 mV

52.8 mV

+5 V

10.2 mV

12.6 mV

14.6 mV

18.2 mV

21.2 mV

+3.3 V

12.6 mV

13.8 mV

16.2 mV

18.6 mV

25.2 mV

+5VSB

5.8 mV

6.4 mV

8.4 mV

10.0 mV

13.0 mV

-12 V

52.2 mV

64.4 mV

70.2 mV

70.2 mV

77.8 mV

Below you can see the waveforms of the outputs during test five.

LEPA G850-MAS
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Figure 22: +12VA input from load tester during test five at 848.4 W (50.4 mV)

LEPA G850-MAS
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Figure 23: +12VB input from load tester during test five at 848.4 W (52.8 mV)

LEPA G850-MAS
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Figure 24: +5V rail during test five at 848.4 W (21.2 mV)

LEPA G850-MAS
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Figure 25: +3.3 V rail during test five at 848.4 W (25.2 mV)

Overload Tests

Below you can see the maximum we could pull from this power supply. The objective of this test is to see if the power supply has its protection circuits working properly. This unit passed this test, as it shut down when we tried to pull more than what is listed in the table below. However, noise and ripple levels were way above the maximum allowed at the +12 V (above 460 mV) and -12 V (above 450 mV) outputs. On the other hand, all positive voltages were still within 3% of their nominal values.

Input

Overload Test

+12VA

33 A (396 W)

+12VB

33 A (396 W)

+5 V

20 A (200 W)

+3.3 V

20 A (66 W)

+5VSB

3 A (15 W)

-12 V

0.5 A (6 W)

Total

956.4 W

% Max Load

112.5%

Room Temp.

46.5° C

PSU Temp.

54.1° C

AC Power

1,147 W

Efficiency

83.4%

AC Voltage

102.6 V

Power Factor

0.996

Main Specifications

The main specifications for the LEPA G850-MAS power supply include:

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

Conclusions

On our tests, the new LEPA G850-MAS presented efficiency between 85.7% and 90.3%, low ripple and noise levels, and all positive voltages were closer to their nominal values than required (3% voltage regulation). However, the most positive point of this power supply is its price, USD 150, which is a terrific price tag for an 850 W power supply with the 80 Plus Gold certification and modular cabling system. Therefore, the LEPA G850-MAS deserves our recommendation.

If you are an observant reader, you will notice that internally, the LEPA G850-MAS is very similar to the Corsair HX 850 W Gold. This similarity, however, is due to the fact that both products are manufactured by the same company, CWT. While Corsair hired CWT to deliver them an exclusive model, LEPA opted for buying a ready-made product. Internally, the Corsair HX 850 Gold uses more powerful active PFC transistors and a higher number of rectifying transistors for the +12 V, +5 V, and +3.3 V outputs. Externally, the model from Corsair provides more cables, including two additional connectors for video cards. Also, we’ve seen lower ripple and noise levels on the Corsair’s model. However, the Corsair model is more expensive. If you won’t need to install three high-end video cards, the LEPA G850-MAS is a terrific option for its price.

Originally at http://www.hardwaresecrets.com/article/LEPA-G850-MAS-Power-Supply-Review/1611


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