Huntkey Green Star 550 W (LW-6550SG) Power Supply Review
Main Specifications
Contents
In Figure 15, you can see the power supply label containing all the power specs.
Figure 15: Power supply label.
This power supply features two +12 V virtual rails distributed like this:
- +12V1 (solid yellow wire): All cables but the ATX12V/EPS12V.
- +12V2 (yellow with black stripe wire): ATX12V/EPS12V connectors.
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.
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 (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.
For the test number five we had to respect the current limits for the +12 V outputs, so we had to pull more power from +5 V and +3.3 V outputs than we’d like to.
| 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 | Fail |
| % Max Load | 20.7% | 39.2% | 59.3% | 77.7% | Fail |
| Room Temp. | 45.4° C | 45.3° C | 45.9° C | 48.6° C | 48.6° C |
| PSU Temp. | 47.9° C | 47.1° C | 48.0° C | 52.9° C | 52.9° C |
| Voltage Stability | Pass | Pass | Pass | Pass | Fail |
| Ripple and Noise | Pass | Pass | Pass | Fail | Fail |
| AC Power | 136 W | 253 W | 393 W | 554 W | Fail |
| Efficiency | 83.5% | 85.3% | 82.9% | 77.1% | Fail |
| Final Result | Pass | Pass | Pass | Fail | Fail |
This power supply exploded when we tried to pull 550 W from it (test number five). On the next page we posted the video and pictures showing this.
During our tests this power supply could only achieve good results when we pulled up to 60% (330 W) from it. Under this circumstance efficiency was between 82.9% and 85.3%, which isn’t bad at all.
The problem was when we pulled 80% from its labeled capacity (440 W) efficiency dropped to 77% and noise and ripple skyrocketed to values far above the maximum allowed. Noise and ripple at +12V1 jumped to 157 mV (from 81.4 mV during test three), jumped to 115 mV (from 51.2 mV during test three) at +12V2 and jumped to 58.1 mV (from 23.6 mV) at +5 V. At +3.3 V noise and ripple was within spec (24 mV). All these numbers are peak-to-peak values and the maximum allowed is 120 mV for the +12 V outputs and 50 mV for the +5 V and +3.3 V outputs. It is interesting to note that Huntkey says this power supply can have a maximum noise level of 200 mV for +12 V and 100 mV for +5 V and +3.3 V. This is ridiculous, as this violates the ATX specification.
Figure 16: Noise level at +12V1 with this power supply delivering 427.3 W (157 mV).
Figure 17: Noise level at +12V2 with this power supply delivering 427.3 W (115 mV).
Figure 18: Noise level at +5 V with this power supply delivering 427.3 W (58.1 mV).
Below you can watch the video from test number five with Huntkey Green Star LW-6550SG.
What exploded were the two switching transistors. When the power supply explodes it means that the primary side is under dimensioned. When the secondary side is under dimensioned the power supply dies silently, because when a rectifier burns the short-circuit protection enters immediately in action shutting down the power supply.
So Huntkey should have used more powerful transistors and added a heatsink to the rectifying bridge, plus using rectifiers with higher current limits for the +12 V output.
Below we have some pictures of the power supply and the switching transistors after the explosion.
Figure 19: Huntkey Green Star LW-6550SG after the explosion.
Figure 20: Huntkey Green Star LW-6550SG after the explosion.
Figure 21: Huntkey Green Star LW-6550SG after the explosion.
Figure 22: Switching transistor after the explosion; see how it cracked.
Huntkey Green Star 550 W (LW-6550SG) power supply specs include:
- ATX12V 2.3
- Nominal labeled power: 550 W
- Measured maximum power: 427 W at 48.6° C.
- Labeled efficiency: 70% minimum.
- Measured efficiency: Between 77.1% and 85.3%.
- Active PFC: No.
- Modular Cabling System: No.
- Motherboard Power Connectors: One 20/24-pin connector and two ATX12V connectors that together form an EPS12V connector.
- Video Card Power Connectors: Two 6-pin connectors.
- Peripheral Power Connectors: Six in two cables.
- Floppy Disk Drive Power Connectors: One.
- SATA Power Connectors: Two.
- Protections: over voltage (OVP, not tested) and short-circuit (SCP, tested and working).
- Warranty: N/A.
- More Information: https://www.huntkey.com
- Average price in the US: We couldn’t find this product being sold in the USA.
Huntkey Green Star 550 W is as flawed as the other members from the Green Star family: LW-6550SG exploded when we tried to pull its labeled power.
When we pulled 80% of the labeled capacity (around 427 W in our tests) efficiency was low at 77% and ripple and noise were above the maximum admissible (157 mV at +12 V and 58 mV at +5 V).
The manufacturer clearly plays with the fact that someone buying this power supply probably won’t pull near half of its labeled capacity (a typical PC with a good video card pulls between 100 W and 150 W). However when we buy a product labeled “550 W” we want it to be able to deliver its labeled power, it doesn’t matter if we are going to pull this amount or not. This is called false advertisement.
And it only provides two SATA power connectors.
Internally it uses the exact same rectifiers for the +12 V outputs as the 400 W and 450 W models from Green Star series. This is ridiculous. Current limits were increased at +5 V and +3.3 V with the use of rectifiers with higher current limit, but nowadays we need more current at +12 V, not at +5 V and +3.3 V. This model uses more powerful switching transistors than these 400 W and 450 W models, but they are still under dimensioned, as they exploded.
If you are looking for a true 550 W power supply don’t buy this product. Take a look at the power supplies we have 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 product line, as we reviewed Huntkey Titan 650 W (Rocketfish 700 W) and it didn’t explode. We will try to review other power supplies from this manufacturer in the near future.