Gigabyte Superb 550P Power Supply Review
By Gabriel Torres on April 7, 2010


Introduction

Gigabyte, the traditional motherboard manufacturer, also has entered the power supply business. Let’s see how Superb 550P (GE-P450P-C2) performs.

Looking the box, a huge disappointment: this unit isn’t a 550 W power supply as you could think from its name, but a 450 W unit with 550 W peak power. We’d expect a Chinese low-end manufacturer to resort to this kind of trick, but a tier 1 motherboard manufacturer trying to deceive its customers is inadmissible. This wouldn’t be a problem if stores like Newegg.com weren’t falling for the trick and listing this unit as being a 550 W power supply. Newegg.com also lists this unit as having 80 Plus certification, however this unit isn’t 80 Plus-certified.

Gigabyte Superb 550P power supply
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Figure 1: 450 W continuous, 550 W peak.

By the way, this unit is manufactured by AcBel Polytech.

Gigabyte Superb 550P power supply
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Figure 2: Gigabyte Superb 550P power supply.

Gigabyte Superb 550P power supply
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Figure 3: Gigabyte Superb 550P power supply.

Gigabyte Superb 550P is 5 ½” (140 mm) deep, using a 120 mm fan on its bottom. This unit features passive PFC, not active, so it still has the 115 V/230 V switch you can see in Figure 2. At least it is based on a more modern topology (single-transistor forward) – most power supplies without active PFC are based on the obsolete half-bridge topology, which presents low efficiency.

No modular cabling system is provided and all cables have nylon protections, but only the one used on the main motherboard cable comes from inside the unit (see Figure 3). All cables use 20 AWG wires, which are thinner than the minimum recommended, except the ATX12V/EPS12V cable, which use 18 AWG wires (the correct gauge to be used). The cables included are:

This configuration is compatible with a 450 W product.

Gigabyte Superb 550P 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 Gigabyte Superb 550P

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. 

Notice the passive PFC coil (“transformer”).

Gigabyte Superb 550P power supply
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Figure 5: Overall look.

Gigabyte Superb 550P power supply
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Figure 6: Overall look.

Gigabyte Superb 550P power supply
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Figure 7: Overall look.

Gigabyte Superb 550P power supply
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Figure 8: Passive PFC coil (“transformer”).

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. 

At least on this stage this unit is flawless, with three Y capacitors, one X capacitor and even one MOV more than the required.

Gigabyte Superb 550P power supply
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Figure 9: Transient filtering stage (part 1).

Gigabyte Superb 550P power supply
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Figure 10: Transient filtering stage (part 2).

In the next page we will have a more detailed discussion about the components used in the Gigabyte Superb 550P.

Primary Analysis

On this page we will take an in-depth look at the primary stage of Gigabyte Superb 550P. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.

This power supply uses two GBU605 rectifying bridges connected in parallel. Each one supports up to 6 A at 100° C if a heatsink is used, which is not the case. At 115 V this unit would be able to pull up to 1,380 W from the power grid; assuming 80% efficiency, the bridges would allow this unit to deliver up to 1,104 W without burning themselves out. Of course we are only talking about this component and the real limit will depend on all other components from the power supply.

Gigabyte Superb 550P power supply
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Figure 11: Rectifying bridges.

The capacitors from the voltage doubler circuit are Japanese from Chemi-Con and labeled at 105° C, a miracle on a power supply without active PFC.

This unit is based on the single-transistor forward topology, using two 2SK2749 power MOSFET transistors connected in parallel on its switching section in order to double the maximum current supported by this stage. Each transistor can deliver up to 7 A at 25° C in continuous mode, or up to 21 A at 25° C in pulse mode (unfortunately the manufacturer doesn’t specify the maximum currents at 100° C). These transistors have a maximum RDS(on) of 1.6 Ω, which is insanely high, meaning they have low efficiency (the higher this number, the lower the efficiency). Wait a minute, wasn’t Gigabyte the first manufacturer to promote the advantages of using transistors with low RDS(on) on their motherboards? Surreal…

Gigabyte Superb 550P power supply
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Figure 12: One of the switching transistors.

The switching transistors are controlled by a UC3843B PWM controller, which is physically located on the primary from the power supply.

Gigabyte Superb 550P power supply
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Figure 13: PWM controller.

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

Secondary Analysis

This power supply has six rectifiers on its secondary heatsink plus an LM7912 voltage regulator for its -12 V output.

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. As an exercise, we can consider a duty cycle of 30% for our calculations.

The +12 V output is produced by two SBR20100CT Schottky rectifiers connected in parallel, each one supporting up to 20 A (10 A per internal diode at 150° C, 0.82 V maximum voltage drop), giving us a maximum theoretical current of 29 A or 343 W for the +12 V output.

The +5 V output is produced by two STPS2045CT Schottky rectifiers connected in parallel, each one supporting up to 20 A (10 A per internal diode at 155° C, 0.84 V maximum voltage drop), giving us a maximum theoretical current of 29 A or 143 W for the +5 V output.

The +3.3 V output is produced by another two STPS2045CT Schottky rectifiers connected in parallel, giving us a maximum theoretical current of 29 A or 94 W for the +3.3 V 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.

Gigabyte Superb 550P power supply
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Figure 14: -12 V voltage regulator and +3.3 V, +5 V and +12 V rectifiers.

The outputs are monitored by a WT7527 integrated circuit, which supports over voltage (OVP), under voltage (UVP) and over current (OCP) protections. The OCP circuit from this chip provides four channels, monitoring +3.3 V, +5 V and two +12 V channels. An LM339 (quad voltage comparator) is also present on the solder side of the printed circuit board.

Gigabyte Superb 550P power supply
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Figure 15: Monitoring integrated circuit.

Gigabyte Superb 550P power supply
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Figure 16: Voltage comparator.

The electrolytic capacitors from the secondary are from Ltec.

Power Distribution

In Figure 17, you can see the power supply label containing all the power specs.

Gigabyte Superb 550P power supply
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Figure 17: Power supply label.

As you can see, according to the label this unit has two +12 V rails. Inside the unit the wires are really separated into two groups, and we could clearly see one current sensor (“shunt”) for each group and since the monitoring integrated circuit has over current protection (OCP) with two +12 V channels, this unit really has two +12 V rails. Click here to understand more about this subject.

The two rails are distributed like this:

This is the typical rail distribution used on power supplies with two +12 V rails and it is good because it separates the CPU (ATX12V/EPS12V connector) from the video card.

Now let’s see if this power supply can really deliver 450 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.

The +12VA and +12VB inputs listed below are the two +12 V independent inputs from our load tester. During this test the +12VA input was connected to the power supply +12V1 rail, while the +12VB input was connected to the power supply +12V2 rail.

Input

Test 1

Test 2

Test 3

Test 4

Test 5

+12VA

3 A (36 W)

6.5 A (78 W)

9.5 A (114 W)

13 A (156 W)

17 A (204 W)

+12VB

3 A (36 W)

6.5 A (78 W)

9.5 A (114 W)

13 A (156 W)

16.5 A (198 W)

+5V

1 A (5 W)

2 A (10 W)

4 A (20 W)

5 A (25 W)

7 A (35 W)

+3.3 V

1 A (5 W)

2 A (6.6 W)

4 A (13.2 W)

5 A (16.5 W)

7 A (23.1 W)

+5VSB

1 A (5 W)

1 A (5 W)

1 A (5 W)

1.5 A (7.5 W)

2 A (10 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

90.9 W

181.9 W

269.0 W

357.4 W

448.4 W

% Max Load

20.2%

40.4%

59.8%

79.4%

99.6%

Room Temp.

45.2° C

44.8° C

45.2° C

47.0° C

45.5° C

PSU Temp.

48.8° C

48.8° C

49.6° C

51.5° C

52.5° C

Voltage Regulation

Pass

Pass

Pass

Pass

Pass

Ripple and Noise

Pass

Pass

Pass

Pass

Pass

AC Power

118.4 W

227.6 W

341.1 W

469.0 W

625.0 W

Efficiency

76.8%

79.9%

78.9%

76.2%

71.7%

AC Voltage

115.3 V

114.3 V

112.2 V

110.9 V

109.3 V

Power Factor

0.625

0.673

0.682

0.688

0.693

Final Result

Pass

Pass

Pass

Pass

Pass

We tested Gigabyte Superb 550P as being a 450 W unit; as such it could deliver its labeled wattage at high temperatures.

The main problem with this unit is its efficiency. Although peaking practically 80% when we pulled between 180 W and 270 W (between 40% and 60% from its labeled maximum wattage), it dropped to around 72% when we pulled 450 W from it.

Voltage regulation, on the other hand, was excellent, with all voltages within 3% of their nominal values – i.e., voltages closer to their “face value” than required (ATX12V specification allows 5% tolerance for positive voltages and 10% for negative voltages). The exception was during test five, when the +12 V outputs dropped below this tighter tolerance, but still within the allowed range.

Noise and ripple, although below the maximum allowed, were a little bit higher than we’d like to see during test five. Below you can see the results for test five. The maximum allowed is 120 mV on +12 V and 50 mV on +5 V and +3.3 V. All these numbers are peak-to-peak figures.

Gigabyte Superb 550P Power Supply
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Figure 18: +12VA input from load tester at 448.4 W (81.2 mV).

Gigabyte Superb 550P Power Supply
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Figure 19: +12VB input from load tester at 448.4 W (77.6 mV).

Gigabyte Superb 550P Power Supply
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Figure 20: +5 V rail with power supply delivering 448.4 W (32.6 mV).

Gigabyte Superb 550P Power Supply
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Figure 21: +3.3 V rail with power supply delivering 448.4 W (28.4 mV).

Let’s see if we can pull more than 450 W from this unit.

Overload Tests

Below you can see the maximum we could pull from this unit. If we tried to pull one extra amp from any output the unit would shut down, showing that its protections are working fine. As we can see, we couldn’t pull 550 W from it. Also pay attention at the ridiculously low efficiency this unit presented during this test.

Input

Overload Test

+12V1

20 A (240 W)

+12V2

20 A (240 W)

+5V

8 A (40 W)

+3.3 V

8 A (26.4 W)

+5VSB

2.5 A (12.5 W)

-12 V

0.5 A (6 W)

Total

532.8 W

% Max Load

118.4%

Room Temp.

48.2° C

PSU Temp.

54.6° C

AC Power

779.0 W

Efficiency

68.4%

AC Voltage

106.9 V

Power Factor

0.687

Main Specifications

Gigabyte Superb 550P power supply specs include:

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

Conclusions

We simply can’t understand why when it comes to power supplies tier 1 motherboard manufacturers prefer to provide low-end products. We’ve seen this happening not only with Gigabyte, but also with MSI and ASUS.

Superb 550P is a decent low-end 450 W unit if you pull between 180 W and 270 W from it, when its efficiency touches 80%. On other load patterns, however, efficiency is too low, preventing us from recommending this unit.

Another thing that counts against this unit is Gigabyte labeling it with its peak power. This, by itself, we think should be illegal everywhere in the world. And to make things worse we couldn’t pull 550 W from it.

Superb 550P is far from being superb and it is too expensive for what it is. For example, you can buy an OCZ StealthXStream 500 W for less and get a far better performance.

Originally at http://www.hardwaresecrets.com/article/Gigabyte-Superb-550P-Power-Supply-Review/968


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