Huntkey V-Power 550 W Power Supply Review
By Gabriel Torres on July 8, 2009


Introduction

If you follow closely our power supply reviews you know that all power supplies from Huntkey Green Star series explode if you try to pull its labeled power (we tested the 350 W, 400 W, 450 W and 550 W models – all exploded, see the reviews to watch the videos from them exploding). Today we tested another model from this same brand: V-Power 550 W. Is it a good power supply or will it have the same fate as its sisters?

Huntkey V-Power 550 W is also known by the part number LW-6550SG, the same part number used by Huntkey Green Star 550 W. This caused a big deal of confusion from our part, as documented here. When we first posted the Green Star 550 W review we thought that we were reviewing V-Power 550 W, since the Green Star model was not being listed on Huntkey’s website anymore and the product with part number LW-6550SG was V-Power 550 W. We got an e-mail from Huntkey explaining that we had made a mistake, and we fixed this. From the exchange of e-mails with Huntkey and a series of events that happened we learned that this company is far from being honest, besides the fact that they lie about the maximum power their power supplies can deliver:

It is good to remember that we have already reviewed a model from a different series (Titan 650 W, sold in the US as the first version of Rocketfish 700 W, RF700WPS, the current version RF700WPS2 is manufactured by CWT) from Huntkey and it survived our tests. So the problems we had with Huntkey products (power supplies exploding while you try to pull its labeled power) so far only happened with members from their Green Star and V-Power series.

By the way, the naming scheme Huntkey uses work like this. "SG" means 140 mm fan and "HG" means 120 mm fan. When the model has a passive PFC circuit then a "P" is added at the end. So an LW-6550HG would be the same unit with a 120 mm fan, and an LW-6550SGP would be the same reviewed unit with passive PFC.

Huntkey V-Power 550 W Power Supply
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Figure 1: Huntkey V-Power 550 W (LW-6550SG).

Huntkey V-Power 550 W Power Supply
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Figure 2: Huntkey V-Power 550 W (LW-6550SG).

This power supply is 6 19/64” (160 mm) deep, features a 140 mm fan on its bottom and doesn’t have active PFC circuit, so Huntkey can’t sell this product in Europe. In Figure 1, you can see that it has a voltage selection switch, feature usually present on models without this circuit.

Only the main motherboard cable has a nylon protection, which doesn’t come from inside the power supply. The included cables are:

The main difference between V-Power 550 W and Green Star 550 W is the cable configuration. V-Power 550 W has four SATA power connectors, while Green Star 550 W has only two. On Green Star 550 W, however, the two video card power connectors are attached to individual cables – which is a better configuration –, while on V-Power 550 W both connectors are attached to the same cable. Green Star 550 W offers six peripheral power plugs, while V-Power 550 W offers only three.

The number of connectors available is good enough for you to build a mainstream PC.

All wires are 18 AWG, which is the correct gauge to be used, except the wires used with the peripheral power plugs, which are 20 AWG (i.e., thinner). All cables measure 19” (48 cm) between the power supply and the first connector on the cable, and then 6” (15 cm) between each connector on the cable on cables that have more than one connector.

Huntkey V-Power 550 W Power Supply
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Figure 3: Cables.

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

A Look Inside The V-Power 550 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.

Here the big shock: this power supply is COMPLETELY IDENTICAL to Green Star 550 W. So the claim made by Huntkey on e-mails they sent us saying that these two power supplies are different is a BIG FAT LIE.

Huntkey V-Power 550 W Power Supply
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Figure 4: Overall look.

Huntkey V-Power 550 W Power Supply
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Figure 5: Overall look.

Huntkey V-Power 550 W Power Supply
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Figure 6: Overall look.

Like Green Star 550 W, this unit also has the curious “350 – 450W” marking printed on it.

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.

This power supply is flawless on this stage, having one extra X capacitor, two extra Y capacitors and one extra coil. This power supply has two MOVs located after the rectification bridge, physically squeezed between the two electrolytic capacitors, which is the usual configuration on power supplies based on the half-bridge design.

Huntkey V-Power 550 W Power Supply
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Figure 7: Transient filtering stage (part 1).

Huntkey V-Power 550 W Power Supply
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Figure 8: Transient filtering stage (part 2).

Huntkey V-Power 550 W Power Supply
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Figure 9: MOV’s.

In the next page we will have a more detailed discussion about the components used in the V-Power 550 W.

Primary Analysis

On this page we will take an in-depth look at the primary stage of V-Power 550 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 if a heatsink is used – which is not the case – but only 3.2 A at 25° C if a heatsink is not used. The difference is outrageous and Huntkey should have added a heatsink on this component. The current limit for this component is simply too low (3.2 A).  At 115 V this unit would be able to pull only up to 368 W from the power grid; assuming 80% efficiency, the bridge would allow this unit to deliver only up to 294 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. This is the same component used on Huntkey Titan 650 W (first version of Rocketfish 700 W, RF700WPS, the current version RF700WPS2 is manufactured by CWT), but at least this other product had a heatsink attached to it, which increased the current limit.

Huntkey V-Power 550 W Power Supply
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Figure 10: Rectifying bridge.

V-Power 550 W uses two 2SC3320 power NPN transistors on its switching section using the half-bridge design, supporting up to 15 A at 25° C (unfortunately the manufacturer from these transistors do not say how much they can deliver at higher temperatures). These are the same transistors used on Green Star 550 W and Titan 650 W (Rocketfish 700 W) from Huntkey. These transistors are more “powerful” than the ones used on the 350 W, 400 W and 450 W versions from Green Star power supplies. Like it happened with Green Star 550 W, these were the components that burned when we tried to pull 550 W from the reviewed power supply.

Huntkey V-Power 550 W Power Supply
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Figure 11: One of the two switching transistors.

The two big electrolytic capacitors from the primary are from Teapo (a Taiwanese company) and rated at 85° C.

Secondary Analysis

Huntkey V-Power 550 W has five Schottky rectifiers on its secondary, two for the +12 V output, one for the +5 V output and two for the +3.3 V output, all identical to the ones used on Green Star 550 W.

Since this power supply uses a half-bridge configuration to calculate the maximum theoretical current each output can deliver is easy: all we need to do is to add the maximum current supported by all diodes.

The +12 V output is produced by two MBR20H100CT Schottky rectifiers connected in parallel, each one capable of handling up to 20 A at 100° C (10 A per internal diode). The Green Star 550 W that we reviewed used two STPS20S100CT rectifiers here, which are the same parts but from a different supplier. The maximum theoretical current the +12 V output from this power supply can deliver is of 40 A or 480 W. Of course this math is just an exercise and the actual limit depends on several other factors. It is important to note that this is the same configuration and rating used by the 400 W and 450 W models from Green Star series.

The +5 V output is produced by one S40D40C Schottky rectifier, which is capable of handling up to 40 A at 100° C (20 A per internal diode). So the maximum theoretical current the +5 V output from this power supply can deliver is of 40 A at 100° C or 200 W. This is exactly the same component used on Green Star 550 W, but it is different component from the 400 W and 450 W models from Green Star series, which use a 30 A (150 W) rectifier.

The +3.3 V output is produced by two STPS2045CT Schottky rectifiers connected in parallel, each one capable of delivering up to 20 A at 155° C (10 A per internal diode). So the maximum theoretical current the +3.3 V output from this power supply can deliver is of 40 A at 155° C or 132 W. This is exactly the same component used on Green Star 550 W, but it is a different component from the 400 W and 450 W models from Green Star series, which use a 30 A (99 W) rectifier.

It is always good to remember that the real current/power limit for each output will depend on other factors, like the coils and the width of the printed circuit board traces.

Huntkey V-Power 550 W Power Supply
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Figure 12: The two +12 V rectifiers, the +5 V rectifier and one of the +3.3 V rectifiers (the other one is on the other side of the heatsink).

The secondary is monitored by an SG6105 integrated circuit, which provides protections such as over voltage (OVP), under voltage (UVP), over power (OPP) and short-circuit (SCP). This integrated circuit is also in charge of controlling the switching transistors from the primary (PWM controller).

Huntkey V-Power 550 W Power Supply
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Figure 13: Monitoring integrated circuit.

The electrolytic capacitors from the secondary are from KSC, Teapo and Fcon and labeled at 105° C, as usual.

As you can see, Huntkey V-Power 550 W is IDENTICAL to Huntkey Green Star 550 W.

Power Distribution

In Figure 14, you can see the power supply label containing all the power specs.

Huntkey V-Power 550 W Power Supply
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Figure 14: Power supply label.

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

This is of course a very limited distribution, because it assumes that the CPU will be pulling the same amount of current/power than all other devices combined, which isn’t true if you have a high-end video card.

Now let’s see if this power supply can really deliver 550 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 out tests the +12V1 input was connected to the power supply +12V1 rail (main motherboard cable, peripheral power connectors and video card auxiliary power connector), while the +12V2 input was connected to the power supply +12V2 rail (EPS12V connector). Thus on this review+12V1 and +12V2 really represent the power supply rails with the same name.

Here we used the exact same configuration we used with Huntkey Green Star 550 W, where we pulled less power from the +12 V outputs during the 550 W test (test number five) than we’d like to just in case this power supply couldn’t handle too much power on its +12 V outputs. Usually what we do in our tests is if the unit survives this load configuration then we make a second full load test pulling more power from +12 V and less from +5 V and +3.3 V.

Input

Test 1

Test 2

Test 3

Test 4

Test 5

+12V1

4 A (48 W)

8 A (96 W)

12 A (144 W)

16 A (192 W)

16 A (192 W)

+12V2

4 A (48 W)

8 A (96 W)

12 A (144 W)

16 A (192 W)

18 A (216 W)

+5V

1 A (5 W)

2 A (10 W)

4 A (20 W)

5 A (25 W)

15 A (75 W)

+3.3 V

1 A (3.3 W)

2 A (6.6 W)

4 A (13.2 W)

5 A (16.5 W)

15 A (49.5 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)

0.8 A (9.6 W)

Total

113.6 W

215.8 W

325.9 W

427.3 W

531.9 W

% Max Load

20.8%

39.6%

59.9%

78.9%

96.7%

Room Temp.

47.1° C

47.9° C

46.2° C

46.0° C

46.0° C

PSU Temp.

45.9° C

47.6° C

46.6° C

46.3° C

46.3° C

Voltage Stability

Pass

Pass

Pass

Pass

Fail

Ripple and Noise

Pass

Pass

Pass

Pass

Fail

AC Power

142.6 W

266.5 W

417.0 W

578.0 W

Fail

Efficiency

80.4%

81.7%

79.0%

75.1%

Fail

AC Voltage

113.5 V

111.3 V

111.1 V

108.2 V

Fail

Power Factor

0.600

0.653

0.695

0.715

Fail

Final Result

Pass

Pass

Pass

Pass

Fail

This power supply burned when we tried to pull 550 W from it (test number five), just like it happened with Green Star 550 W. After all, they are the same power supply with different labels. This time there was no explosion, though. After 45 seconds on test five we heard a loud low-frequency hum and the fuses from our load tester blew. After disassembling the power supply we tested all components and the two switching transistors were burned, just like it happened with all other power supplies from Green Star series when we tried to pull its labeled power.

Efficiency was above 80% only when we pulled up to 40% from its labeled power (i.e., up to 220 W). During test four electrical noise on +12V1 rail was very high (105.6 mV), but still inside the 120 mV limit. All other outputs presented low noise level (54.2 mV on +12V2, 23.8 mV on +5 V and 17.6 mV on +3.3 V) during the same test.

Power factor was low since this unit does not have a power factor correction (PFC) circuit. Units with active PFC present a power factor of at least 0.98.

Main Specifications

Huntkey V-Power 550 W power supply specs include:

Conclusions

Huntkey V-Power 550 W is a Green Star 550 W with a different label and a slightly different cable configuration. And that’s it. This explains why V-Power 550 W and Green Star 550 W have the same model number (LW-6550SG).

Like all members from Green Star family, V-Power 550 W burns if you try to pull its labeled power continuously at a room temperature around 45° C.

It was really ridiculous to see Huntkey saying to us that V-Power 550 W and Green Star 550 W were different products.

If you are looking for a true 550 W power supply don’t buy this product. Take a look at the list of power supplies we already tested and that got an award seal for choosing a good product that won’t explode or damage your equipment.

Keep in mind that this problem seems to be specific with the Green Star and V-Power products, as we reviewed Huntkey Titan 650 W (first version of Rocketfish 700 W, RF700WPS, the current version RF700WPS2 is manufactured by CWT) and it didn’t explode.

Originally at http://www.hardwaresecrets.com/article/Huntkey-V-Power-550-W-Power-Supply-Review/754


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