Rocketfish 700 W Power Supply Review
By Gabriel Torres on May 16, 2008


Introduction

Rocketfish and Dynex are two brands owned by Best Buy sold only on their chain of retail stores (and also on their website, of course). Today we are going to review Rocketfish 700 W, a power supply featuring two auxiliary power cables for video cards, active PFC and a 120 mm fan. Costing USD 165, is it worth the price? Can it really deliver 700 W? Read on.

Rocketfish and Dynex power supplies are manufactured by Huntkey, and we were very curious to review these power supplies from Best Buy for two reasons. First, with more than 1,000 stores worldwide you can find at least one Best Buy store in every major American city. So these power supplies can be found on every corner of the country. Second, we had already reviewed a Huntkey power supply that couldn’t deliver its labeled power, so we were really interested in knowing if that was a problem with that particular model or if all Huntkey models are labeled with a power capacity higher than they can actually deliver.

Rocketfish 700 W is rebadged Huntkey Titan 650 W (HK650-52PEP). Hum... The original manufacturer says this is a 650 W power supply, so can it really deliver 700 W? Wait and see...

Rocketfish 700 W Power Supply
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Figure 1: Rocketfish 700 W power supply.

Rocketfish 700 W Power Supply
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Figure 2: Rocketfish 700 W power supply.

On Best Buy and Rocketfish websites the complete specifications for this power supply is missing. In fact, the box and the websites bring conflicting information: both websites say that this is an ATX12V 2.0 power supply, while the product box and label say it is an ATX12V 2.2 product. The box also lists all protections present on this power supply, while the websites and the product manual fail to list them. Efficiency is only mentioned on the product box (80%), but active PFC is mentioned everywhere.

This power supply comes with a 24-pin motherboard cable (it comes with an adapter for you to convert this plug into a 20-pin one), an ATX12V cable, an EPS12V cable and six peripheral cables: two auxiliary power cables for video cards with 6-pin connectors, one cable with four standard peripheral power connectors, one cable with three standard peripheral power connectors and one floppy disk drive power connector and two cables with three SATA power plugs each.

The number of cables is adequate even for the exigent user.

On this power supply all wires are 18 AWG but the ones used on the SATA power cables, which are 20 AWG (i.e., thinner). Also on the peripheral cables the wires coming from inside the power supply are 18 AWG but the wires connecting the first plug to the other plugs are 20 AWG. We’d like to see all wires being 18 AWG.

On the aesthetic side all wires are protected with a nylon sleeving, but this protection doesn’t come from inside the power supply housing.

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

A Look Inside The Rocketfish 700 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.

From this first look we could clearly see that Rocketfish 700 W had absolutely nothing to do with the other model from Huntkey we reviewed (Green Star 450 W); they use completely different designs.

Rocketfish 700 W Power Supply
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Figure 3: Overall look.

Rocketfish 700 W Power Supply
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Figure 4: Overall look.

Rocketfish 700 W Power Supply
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Figure 5: 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.

On this stage this power supply is flawless, providing two extra Y capacitors, one extra X capacitor and a ferrite bead attached to the main AC cable.

Rocketfish 700 W Power Supply
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Figure 6: Transient filtering stage (part 1).

Rocketfish 700 W Power Supply
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Figure 7: Transient filtering stage (part 2).

In the next page we will have a more detailed discussion about the components used in the Rocketfish 700 W.

Primary Analysis

On this page we will take an in-depth look at the primary stage of Rocketfish 700 W. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.

This power supply uses one T15XB80 rectifying bridge in its primary, capable of delivering up to 15 A at 100° C with a heatsink, which is the case. 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.

Rocketfish 700 W Power Supply
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Figure 8: Rectifying bridge.

The active PFC circuit uses two SPW20N60C3 power MOSFET transistors, each one capable of handling up to 13.1 A in continuous mode at 100° C (or 20.7 A at 25° C; see the difference temperature makes) or 62.1 A in pulse mode at 25° C. These transistors are located on the same heatsink as the switching transistors.

On the switching section this power supply uses regular power NPN transistors and not power MOSFET transistors in the two-transistor foward configuration. Usually power supplies based on this kind of transistor presents lower efficiency. Two 2SC3320 are used, each one capable of delivering up to 15 A at 25° C.

Rocketfish 700 W Power Supply
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Figure 9: Switching transistors, PFC diode and active PFC transistor (the other active PFC transistor is on the other side of the heatsink).

The primary section is controlled two separated integrated circuits, one for the active PFC circuit (ICE2PCS01) and one for driving the switching transistor (i.e., PWM, AZ7500B integrated circuit), instead of using just one combo controller as it happens with almost all modern power supplies.

Rocketfish 700 W Power Supply
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Figure 10: Active PFC controller.

Secondary Analysis

This power supply uses one of the most unusual configurations we’ve ever seen on its secondary. We decided to draw a simplified schematics from the secondary so you can better understand the configuration used on this power supply. Read our Anatomy of Switching Power Supplies tutorial to compare the configuration used on this power supply with the configuration normally used. In the name of simplification we didn’t draw the controlling circuit of the MOSFET transistors and that is why we left their gates unconnected.

Rocketfish 700 W Power Supply
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Figure 11: Secondary from Rocketfish 700 W.

The +12 V output is produced by three Schottky rectifier packs. Two STPS30150CW are in charge of the rectification, while one STPS4045CW is in charge of the freewheeling diodes. This is a very unusual design, as usually power supplies use the same number of rectifying and freewheeling diodes and also they are usually identical. Here we have four diodes for the direct rectification and two diodes for freewheeling part.

Because of this asymmetrical design, we have to consider the part with lower current limit in our calculation. This would be the freewheeling path, which has two 20 A diodes in parallel. The maximum theoretical current the +12 V 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 diode (which in this case is made by two 20 A diodes in parallel, as mentioned). Just as an exercise, we can assume a typical duty cycle of 30%. This would give us a maximum theoretical current of 57 A or 686 W for the +12 V output. The maximum current this line can really deliver will depend on other components, in particular the coil used.

The +5 V output is rectified using a synchronous topology, while the +3.3 V is rectified using a partial synchronous topology, where only the freewheeling diode was replaced by a power MOSFET transistor: the rectification diode wasn't replaced like in a full synchronous topology. The transistors used are IRL7833 power MOSFET transistor, which can handle 110 A at 100° C each and the +3.3 V output is rectified through an SBL4040PT Schottky rectifier (40 A at 100° C, 20 A per internal diode).

As an exercise we can try to calculate the maximum theoretical current/power also for the +5 V and +3.3 V outputs. For the +5 V output the current limit would be of 157 A with 786 W maximum power and for the +3.3 V output the current limit would be of 29 A with 94 W maximum power. In both cases we are assuming a 30% duty cycle.

The use of this partial synchronous design is really intriguing, as this design in theory offers a higher efficiency (the reason why is that MOSFET transistors usually offer a lower voltage drop compared to Schottky rectifiers, i.e., less wasted power), but at the same time Huntkey used regular BJT transistors on the switching section. Go figure.

Rocketfish 700 W Power Supply
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Figure 12: +12 V negative rectifier, transistor and +3.3 V rectifier.

Rocketfish 700 W Power Supply
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Figure 13: Transistors and +12 V rectifiers.

For the protection circuit instead of using a monitoring integrated circuit this power supply uses a discrete protection circuit, i.e., the manufacturer created their own protection circuit instead of using an off-the-shelf integrated circuit. For this circuit three quad-comparators integrated circuits (AS339) are used. These integrated circuits are located on a small printed circuit board located on the secondary. Because of the use of a customized circuit we couldn’t check exactly what protections this power supply really had (well, we could if we spent a lot of time analyzing this circuit). We could clearly see the over current protection (OCP) circuit, as we will explain in the next page.

Rocketfish 700 W Power Supply
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Figure 14: Protection circuit.

All electrolytic capacitors are Taiwanese, Teapo, KSC, Fcon

The active PFC electrolytic capacitors are rated at 85° C (and manufactured by Teapo, a Taiwanese company), while the electrolytic capacitors from the secondary are rated at 105° C and coming from several vendors (Teapo, Fcon and KSC).

Power Distribution

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

Rocketfish 700 W Power Supply
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Figure 15: Power supply label.

As you can see this power supply has four virtual +12 V rails. We could clearly see on the printed circuit board that each rail was really connected to the over current protection (OCP) circuit. The only wires that use a different color are the wires connected to the +12V4 rail.

These rails are distributed like this:

The power distribution on this power supply is simply perfect, as with four rails the manufacturer could use individual rails for each main device (video cards and processor).

Now let’s see if this power supply can really deliver 700 W of power.

Load Tests

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

Usually we test power supplies with five different load patterns, trying to pull around 20%, 40%, 60%, 80%, and 100% of its maximum capacity (actual percentage used listed under “% Max Load”), watching how the reviewed unit behaved under each load.

But since we had a bad experience with a different unit from Huntkey and also because this model is labeled by Huntkey as a 650 W product and not a 700 W one, we decided to add other load patterns to our methodology, including other loads between 80% and 100% of the power supply maximum labeled power.

We broke the results down into two tables. On the first table you see the results for loads between 20% and 80%, and on the second table you see the results for loads between 80% and 100%. Below we will explain more about this second table.

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.

+12V2 is the second +12V input from our load tester and during our tests it was connected to the power supply EPS12V – i.e., to the +12V4 rail. The +12V1 input was connected to the +12V2 and +12V3 rails.

Input

Test 1

Test 2

Test 3

Test 4

+12V1

5 A (60 W)

11 A (132 W)

16 A (192 W)

21 A (252 W)

+12V2

5 A (60 W)

10 A (120 W)

16 A (192 W)

20 A (240 W)

+5V

1 A (5 W)

2 A (10 W)

4 A (20 W)

6 A (30 W)

+3.3 V

1 A (3.3 W)

2 A (6.6 W)

4 A (13.2 W)

6 A (19.8 W)

+5VSB

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)

Total

173.7 W

350.5 W

514.0 W

589.0 W

% Max Load

20.0%

40.1%

61.1%

78.3%

Room Temp.

48.7° C

48.9° C

48.2° C

46.4° C

PSU Temp.

53.1° C

52.8° C

51.6° C

52.1° C

Load Test

Pass

Pass

Pass

Pass

Voltage Stability

Pass

Pass

Pass

Pass

Ripple and Noise

Pass

Pass

Pass

Pass

AC Power

169 W

337 W

527 W

701 W

Efficiency

83.0%

83.2%

81.2%

78.2%

Final Result

Pass

Pass

Pass

Pass

Up to 80% load we saw a blue sky, but we were afraid that this power supply would burn or explode if we pulled 700 W from it. So we decided to pull 600 W and 650 W from it before trying to pull the full 700 W. So we have patterns five and six reflecting these loads. Then we have three patterns for the 100% load test. With our first 100% pattern, test number seven, we respected the power limits printed on the power supply label: 509 W for the +12 V outputs and 170 W for the +5 V and +3.3 V outputs combined. But with this pattern the power supply was delivering a little bit less than 700 W, so we decided to increase current on +3.3 V in order to get closer to 700 W (test number eight).

The problem with tests seven and eight is that in order to respect the power supply limits we were pulling a lot of power from +5 V and +3.3 V and not as much power as we wanted from +12 V. This scenario does not reflect a typical computer usage from nowadays, where load is concentrated on +12 V outputs due to the system CPU (ATX12V/EPS12V connectors) and video cards, which are connected to the +12 V line and not to +5 V and +3.3 V ones.

So with test number nine we tested this power supply with its full load the way we like: pulling a lot of power from +12 V outputs and less from +5 V and +3.3 V.

See the results below.

Input

Test 5

Test 6

Test 7

Test 8

Test 9

+12V1

21 A (252 W)

21 A (252 W)

21 A (252 W)

21 A (252 W)

26 A (321 W)

+12V2

20 A (240 W)

20 A (240 W)

21 A (252 W)

21 A (252 W)

24 A (288 W)

+5V

12 A (60 W)

17 A (85 W)

21 A (105 W)

21 A (105 W)

10 A (50 W)

+3.3 V

12 A (39.6 W)

17 A (56.1 W)

19 A (62.7 W)

21 A (69.3 W)

10 A (33 W)

+5VSB

2.5 A (12.5 W)

2.5 A (12.5 W)

3 A (15 W)

3 A (15 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

602.0 W

656.0 W

688.0 W

695.0 W

683.0 W

% Max Load

86.0%

93.7%

98.3%

99.3%

97.6%

Room Temp.

47.4° C

51.4° C

47.3° C

46.4° C

51.2° C

PSU Temp.

53.3° C

57.° C

52.8° C

52.5° C

60.° C

Load Test

Pass

Pass

Pass

Pass

Pass

Voltage Stability

Pass

Pass

Pass

Pass

Pass

Ripple and Noise

Pass

Pass

Pass

Pass

Pass

AC Power

789 W

882 W

936 W

944 W

920 W

Efficiency

76.3%

74.4%

73.5%

73.6%

74.2%

Final Result

Pass

Pass

Pass

Pass

Pass

We were impressed to see that Rocketfish 700 W can really deliver its labeled power at 50° C. Not bad at all!

But, as we constantly say, power isn’t everything. You will only achieve efficiency above 80% if you pull up to 60% of this power supply maximum capacity (i.e., below 420 W). With 80% load (560 W) we saw a 78% efficiency, dropping below that on the other load patterns we used for loads between 560 W and 700 W (see table above).

Voltage stability was very good, with all outputs between 3% of their nominal voltage in almost all tests, which is excellent (ATX standard allows voltages to be up to 5% from their nominal values – 10% in the case of the -12 V output).  We only saw voltages outside this 3% range on tests 7, 8 and 9 on +5 V and -12 V, but they were still inside the maximum allowed.

Ripple and noise increased with load. For example, on test one noise at +12V1 input from our load tester was at 17.2 mV, jumping to 92.6 mV during test nine. Even with this increase, noise was inside specs during all tests (i.e., up to 120 mV peak-to-peak at +12 V and up to 50 mV peak-to-peak at +5 V and at +3.3 V).

On the screenshots below we show noise level for test number eight, with our power supply delivering practically 700 W.

Rocketfish 700 W Power Supply
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Figure 16: Noise level at +12V1 input from load tester at 695 W (83.6 mV).

Rocketfish 700 W Power Supply
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Figure 17: Noise level at +12V2 input from load tester at 695 W (83.2 mV).

Rocketfish 700 W Power Supply
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Figure 18: Noise level at +12V2 input from load tester at 695 W (30.6 mV).

Rocketfish 700 W Power Supply
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Figure 19: Noise level at +12V2 input from load tester at 695 W (17 mV).

Of course we wanted to see lower values here, especially for a power supply that costs USD 165. Good power supplies are capable of producing far less noise, half of the amount presented by this unit or even less.

Now let’s see if we could pull even more power from this unit and our tests of the power supply protections.

Overload Tests

Before performing our overload tests we always like to test first if the over current protection (OCP) circuit is really active and at what level it is configured.

We configured +12V1 input from our load tester with a low current (1 A) and increased current on +12V2 input (which was connected to the power supply +12V4 rail through the EPS connector) until the power shut down. This happened when we tried to pull more than 22 A, so OCP was active and set at 22 A. Funny enough with our power supply fully loaded we could pull more than that and the power supply didn’t shut down. See test nine in the previous page.

Then we tried to pull even more power from Rocketfish 700 W. We were brave enough to try pulling 770 W from it, as you can see in the table below.

Input

Maximum

+12V1

24 A (288 W)

+12V2

24 A (288 W)

+5V

22 A (110 W)

+3.3 V

22 A (72.6 W)

+5VSB

3 A (15 W)

-12 V

0.5 A (6 W)

Total

770 W

% Max Load

110%

Room Temp.

48.2° C

PSU Temp.

57.8° C

Load Test

Pass

Voltage Stability

Pass

Ripple and Noise

Pass

AC Power

1,085 W

Efficiency

71%

Final Result

Pass

Efficiency was very low, 71%. See how we were pulling over 1,000 W from the wall in order to generate 770 W. Noise level was almost touching the limit, at 100 mV on +12 V outputs.

Short circuit protection (SCP) worked fine for both +5 V and +12 V lines.

Main Specifications

Rocketfish 700 W power supply specs include:

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

Conclusions

We were expecting to burn or explode this power supply but, hey, it survived to our load tests! So it isn’t as bad as we originally thought (and proved that not all Huntkey power supplies are a piece of you-know-what). We could really extract 700 W from it at 50° C, so at least its label isn’t a lie, especially when we think that this model is originally labeled as a 650 W by the original manufacturer (Huntkey).

However, power isn’t everything. Ripple and noise levels were far above we wanted to see, it doesn’t come with four video card cables, the video card cables don’t use 6/8-pin connectors and comes with just one year warranty (all power supplies from well-known manufacturers come with at least 3-year warranty in the United States). These flaws can’t be tolerated on a USD 165 product.

USD 165? Wait a minute… Are these guys crazy? We can buy a PC Power & Cooling Silencer 750 Quad for less than that! Just to remember this PC Power & Cooling unit has far higher efficiency, lower noise level, a far higher maximum power, four video card cables and a five-year warranty.

Rocketfish 700 W would be a terrific product if it cost USD 70, tops. But at USD 165 it makes absolute no sense buying this unit.

Originally at http://www.hardwaresecrets.com/article/Rocketfish-700-W-Power-Supply-Review/556


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