Huntkey Green Star 450 W (LW-6450SG) Power Supply Review
By Gabriel Torres on March 24, 2008
Huntkey is a brand that isn’t known by the North-American audience but it is somewhat popular in other countries, due to the low cost of its products. Huntkey manufactures some power supplies for other brands sold in the US, in particular BestBuy-owned Dynex and Rocketfish. We completely dissected their Green Star 450 W (LW-6450SG) model and tested to see if it can really deliver its labeled power. Read on.
As you can see, this power supply uses a big 140 mm fan on its bottom (the power supply is upside down in Figure 2) and a big mesh on the rear side where traditionally we have an 80 mm fan. We like this design as it provides not only a better airflow but the power supply produces less noise, as the fan can rotate at a lower speed in order to produce the same airflow as an 80 mm fan.
This power supply, however, doesn’t have active PFC. In practical terms this only means that Huntkey can’t sell this product in Europe (you can read more about PFC on our Power Supply Tutorial).
As for efficiency, Huntkey says on the product box that “efficiency exceeds 85% under full load.” On their website, however, a funny thing happens. They say “85% high efficiency performance” but under “Output Spec” they say “70% min at full load 230 VAC/50 Hz, 50% min at 30 W load 230 VAC/50 Hz,” which makes much more sense. Of course we will test to see if this is true or not.
The higher the efficiency the better – an 80% efficiency means that 80% of the power pulled from the power grid will be converted in power on the power supply outputs and only 20% will be wasted. This translates into less consumption from the power grid (as less power needs to be pulled in order to generate the same amount of power on its outputs), meaning lower electricity bills – compare to less than 70% on regular power supplies.
This power supply comes with four peripheral power cables: one auxiliary power cable for video cards with 6-pin connector, one cable containing three standard peripheral power connectors and one floppy disk drive power connector, one cable containing three standard peripheral connectors and one cable containing two SATA power connectors.
The number of connectors is enough for a mainstream user that won’t have more than two SATA devices willing to build an entry-level or mainstream PC with a good video card. However, users with more than two SATA devices (i.e., more than two hard drives) will need to use adapters.
The main motherboard cable uses a 20/24-pin connector, and this power supply has one EPS12V connector that can be transformed into an ATX12V connector, as you can see in Figure 3.
On the aesthetic side Huntkey used nylon sleeving only on the main motherboard cable, and it doesn’t come from inside the power supply housing.
But the main problem with the cables used on this power supply is that they use wires thinner than we’d like to see. We think all power supplies should use 18 AWG wires, with high wattage units using 16 AWG ones, but on this power supply all peripheral cables are 20 AWG, including the video card cable. The motherboard cables, however, are 18 AWG.
A curious detail is that the UL registration number at this power supply label is E181356, which belongs to "SHENZHEN CHI YUAN INDUSTRIAL CO LTD", which is Huntkey’s registered company name. But on the product box the UL registration that is printed is E175472, which belongs to Fore Point, a company from another group. Of course the number printed on the box is wrong, but this a very strange error.
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.
In this page, we will have an overall look, while in the next page we will discuss in details the quality and rating of the components used.
The first impression we had when opening this power supply was that we were in front of a very low-end (“generic”) unit that was put inside a nice housing as the printed circuit board was too small for the size of the housing, as you can see in Figure 4. Let’s see if this was just an impression or if there is some truth about our hunch.
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 Huntkey Green Star 450 W is flawless: it has one extra ferrite coil, two extra Y capacitors and one extra X capacitor.
When we first posted this review we said that this power supply didn't have a MOV. In fact it has two MOV's but since they are located in a non-traditional location (after the rectifying bridge and not before as usual) we didn't see them at the first time we disassembled this unit. We ask you our sincere apologies for this mistake.
A very interesting feature from this power supply is that its fuse is inside a fireproof rubber protection. So this protection will prevent the spark produced on the minute the fuse is blown from setting the power supply on fire.
In the next page we will have a more detailed discussion about the components used in the Huntkey Green Star 450 W.
We were very curious to check what components were chosen for the power section of this power supply and also how they were set together, i.e., the design used. We were willing to see if the components could really deliver the power announced by Huntkey.
This power supply uses one D15XB80 rectifying bridge in its primary stage, which can deliver up to 3.2 A (rated at 25° C) without a heatsink installed, which was the case. If Huntkey had attached a heatsink to this bridge its maximum current would be 15 A at 100° C. This is definitely something Huntkey should have done, because this bridge is limiting the maximum amount of current this power supply can deliver. At 115 V this unit would be able to pull only up to 368 W (115 V x 3.2 A) from the power grid; assuming 80% efficiency, the bridge would allow this unit to deliver only up to 294 W without burning this component. This is ridiculous and a hint that something is wrong with the project from this power supply.
click to enlarge
Figure 9: Rectifying bridge.
In the switching section, two FJP13009 NPN power transistors are used in a half-bridge configuration. They can deliver up to 12 A continuous mode or up to 24 A in pulse mode, which is the case. Both values are given at 25° C. This old configuration is typical on power supplies without active PFC and usually power supplies based on this topology present lower efficiency.
This power supply uses four Schottky rectifiers on its secondary.
On power supplies based on half-bridge topology calculating the maximum theoretical current/power is easy: we just need to add the maximum current supported by all diodes connected to a given output.
The +12 V output is produced by two STPS20S100CT Schottky rectifiers connected in parallel, which can deliver up to 20 A each (10 A per diode, measured at 150° C), thus the maximum theoretical current the +12 V line can deliver is of 40 A, which equals to 480 W at 150° C. The maximum current this line can really deliver will depend on other components.
The +5 V output is produced by one STPS30S45CW Schottky rectifier, which support up to 30 A (15 A per diode, measured at 135° C). So the maximum theoretical power the +5 V output can deliver is of 150 W. Of course the maximum current (and thus power) this line can really deliver will depend on other components.
The +3.3 V output is produced by another STPS30S45CW Schottky rectifier, which support up to 30 A (15 A per internal diode, measured at 140° C). So the maximum theoretical power the +3.3 V output can deliver is of 99 W. Of course the maximum current (and thus power) this line can really deliver will depend on other components.
Even though this power supply has a separated rectifier for the +3.3 V output, this rectifier is connected to the same transformer output as the +5 V line, so the maximum current +5 V and +3.3 V can pull together is limited by the transformer.
This power supply thermal sensor is located close to one of the ends of the secondary heatsink, as you can see in Figure 12. This sensor is used to control the fan speed according to the power supply internal temperature and also to shut it down if the power supply implements over temperature protection (OTP) – the majority of power supplies on the market, including the reviewed unit, don't have this protection.
On this power supply the big electrolytic capacitors from the voltage doubler 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).
In Figure 13, you can see Huntkey Green Star 450 W label stating its power specs. The information present on the box is more complete than the one present on the label, so we included a picture of the specs present on the box as well. Comparing the two pictures you can see the difference on the UL registration number we mentioned on the first page.
As you can see this power supply has two virtual rails, the first one rated at 15 A and the second one rated at 17 A. The only thing connected to the second rail is the EPS12V/ATX12V connector, which is fine for a power supply from this power range. Inside the power supply we could see a separated filtering circuit for each rail (a coil and a capacitor), which was really interesting to see.
Now let’s see if this power supply can really deliver 450 W of power.
We conducted several tests with this power supply, as described in the article Hardware Secrets Power Supply Test Methodology. All the tests described below were taken with a room temperature between 44° C and 48° C. During our tests the power supply temperature was between 49° C and 53° C.
First we tested this power supply with six different load patterns, trying to pull around 20%, 40%, 60%, 80%, and 100% (two patterns) 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.
For the 100% load testing we used two different load patterns and we need to explain why. The load pattern used on our test five was created in order to simulate a typical PC usage today, with most power being pulled from the 12 V outputs, because the CPU (through ATX12V and EPS12V connectors) and the video card (through auxiliary PCI Express connector) are connected to them. This configuration, however, surpassed the maximum specs printed on the product box – 286 W for the +12 V outputs (we were pulling 384 W during this pattern). During this test our power supply exploded (more precisely the switching transistors burned).
Even though we knew that when the switching transistors burn the problem is with the overall power (which is higher than the maximum supported by the power supply) and not with any of the individual power supply outputs being overloaded (because when this happens the secondary rectifiers are the components that burn) we decided to re-test this power supply respecting its maximum limits printed on the product box. To do that we bought a new power supply and reconfigured our load test to use test number six as the test for maximum load for this power supply. The result was what we expected: our second power supply exploded just like the first one since, like we explained, the problem wasn’t on the power configuration of the outputs but with the power supply maximum overall power. This time we taped the test and we will talk more about it below.
+12V2 is the second +12V input of our load tester and on this test it was connected to the power supply EPS12V connector. Since this connector was the only one connected to the power supply +12V2 rail, the +12V1 and +12V2 inputs from our load tester were really connected to the +12V1 and +12V2 virtual rails from the reviewed power supply.
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.
|Input||Test 1||Test 2||Test 3||Test 4||Test 5||Test 6|
|+12V1||3 A (36 W)||6.5 A (78 W)||10 A (120 W)||13 A (156 W)||17 A (204 W)||12 A (144 W)|
|+12V2||3 A (36 W)||6.5 A (78 W)||9 A (108 W)||12.5 A (150 W)||15 A (180 W)||11.5 A (138 W)|
|+5V||1 A (5 W)||2 A (10 W)||4 A (20 W)||5 A (25 W)||6 A (30 W)||18 A (90 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)||16.5 A (54.45 W)|
|+5VSB||1 A (5 W)||1 A (5 W)||1 A (5 W)||1.5 A (7.5 W)||2 A (10 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)||0.5 A (6 W)|
|Total||90.3 W||181.4 W||269.7 W||356.9 W||449.9 W||451 W|
|% Max Load||20.1%||40.3%||59.9%||79.3%||99.9%||100.2%|
|Ripple and Noise||Pass||Pass||Pass||Pass||Fail||Fail|
Like we said Huntkey 450 W (LW-6450SG) exploded when we tried to pull 450 W from it using a load pattern that respects the limits printed on the product box (test six) and also using a load pattern that pulls more power from 12 V outputs and less power from 5 V and 3.3 V outputs (test five). This means that this power supply isn’t capable of delivering its labeled power in continuous mode being, as matter of fact, a 360 W power supply.
You can follow our test number six (i.e., our test with the second power supply we bought) on the below video. On this video you first see how our load tester was configured, which is exactly what is described on the table above on the “test 6” column. Then we changed the machine to display the power being pulled by the power supply and, after that, we turn on the CA main power from the power supply. The power supply was initially turned off and delivering only standby voltage (+5VSB). Then we turned on our power supply and you can see it pulling 450 W from our load tester. On top of the load tester there is our thermometer, showing the power supply temperature (above) and the temperature inside our “hot box” (below). It is hard to read it because of the video compression, but when we turned on the power supply temperature inside the box was around 41.5° C, below what we wanted for our methodology (we always test power supplies with a room temperature between 45° C and 50° C). In less than 2 minutes the power supply explodes. Check it out. In order to not being accused of uploading a fake video, we didn’t make any kind of editing and that’s why we didn’t put our logo or any text explaining what is going on.
When we opened the power supply we tested all main components and found out that the two switching transistors and two of their bias resistors had burned, check out on the pictures below the evidences we found.
Keep in mind that we have already posted reviews of two other power supplies that use the same old design used by this unit (Seventeam ST-420BKV and Kingwin ABT-450MM), but contrary to this Huntkey model these units could deliver their rated power. Also both power supplies shut down when we tried to pull much more power that they can deliver, as their protections kicked in.
Another power supply from this same power range that we have recently reviewed and that couldn't deliver its labeled power was Thermaltake PurePower 430 W NP, which is in fact a 350 W power supply. But this model from Thermaltake didn't explode when we tried to pull 430 W, as the over power protection (OPP) circuit entered in action.
Another clear problem was efficiency. On the product box the manufacturer says that “efficiency exceeds 85% under full load,” which is a lie. On their website, however, they say this power supply has a minimum efficiency of 70% under full load and 50% under 30 W load, which makes more sense. Efficiency was between 80.6% and 84.4% during tests 1, 2 and 3, dropping to 73.6% during test 4, where we were pulling 80% of the maximum labeled power (357 W). We couldn’t measure efficiency under full load as the power supply exploded. So if you pull only up to 270 W this power supply will have an excellent efficiency.
On the tests the power supply worked correctly, voltages were really stable, inside a 3% limit from the nominal voltage – which is really great, as the limit is 5% –, except the -12 V output. This output was at -11.20 V and -11.41 on tests 1 and 2. Even though ATV12V standard sets -12 V tolerance at 10% (which means it can go from -10.80 V to -13.20 V) we would like to see this output closer to the nominal -12 V voltage.
Even though electrical noise was low during tests 1, 2 and 3 (below 12 mV on +5 V and +3.3 V rails and between 33.8 mV and 45.6 mV at +12V1 and between 42.4 mV and 59 mV at +12V2), it increased a lot during test 4, with noise on +12V2 rail reaching 90.4 mV (the limit is 120 mV).
Unfortunately we couldn’t capture screenshots from ripple and noise this time as the power supply exploded.
Huntkey Green Star 450 W (LW-6450SG) power supply specs include:
Huntkey Green Star 450 W (LW-6450G) is in fact a 360 W power supply. This wouldn't be a problem if the power supply didn't explode if you try to pull 450 W from it (we tested two power supplies with two different 450 W load patterns). Also while delivering 360 W its efficiency drops below 80% and its electrical noise increases a lot, but still inside specs.
If you use this power supply with a PC that pulls only up to 270 W it will have an excellent efficiency.
This is without questioning the worst "branded" power supply we've seen. Thermaltake PurePower 430 W NP is another power supply that can't deliver its labeled power, but at least this Thermaltake model doesn't explode if you try to pull its labeled power.
This is probably the worst “branded” power supply we’ve seen in our life:
Does this mean that Huntkey is making false claims and should be sued? Unfortunately no, as the manufacturer doesn’t say the methodology they used to label their power supply – maybe they labeled the unit inside a freezer in China, who knows? The fact is that under real-world conditions, with a room temperature between 45° C and 50° C this power supply can't deliver 450 W continously.
In summary, would you buy a 450 W power supply that can only deliver 360 W and explodes if you try to pull more than that?