[nextpage title=”Introduction”]
To start off, we must say that we were really disappointed with the name chosen by Arctic Cooling for this product. 550RF leads you to believe that this is a 550 W product, when in fact it is a 500 W power supply. The 550 W on the name is the peak power, which according to the manufacturer can be sustained for only ONE SECOND. This kind of gimmick is typically used by low-end manufacturers and we wouldn’t expect this from a Switzerland-based company. But besides that, is Fusion 550RF a good product? Let’s see.
Fusion 550RF is in reality manufactured by Seasonic and it is internally identical to Corsair VX450W and Antec Earthwatts 500 W, two power supplies we reviewed and achieved excellent results. But here you can see how the same 500 W power supply can be labeled differently by three different brands (450 W vs. 500 W vs. 550 W), which Corsair being conservative, Antec being realistic and Arctic Cooling being exaggerated.
This model from Arctic Cooling, however, uses a high-end 80 mm ARCTIC F8 Pro fan, which is based on fluid dynamic bearing. Together with the rubber shock absorber it uses, it provides a lower noise level, according to the manufacturer. Unfortunately we don’t have a noise meter to test this. Inside the power supply the airflow produced by the fan is channeled through a “tunnel,” as we you show you later.
The reviewed unit is only 5 1/2” (140 mm) deep, however its fan is installed outside the housing, adding 1 inch (2.5 cm) to the total depth of the power supply.
Figure 1: Arctic Cooling Fusion 550RF power supply.
Figure 2: Arctic Cooling Fusion 550RF power supply.
A unique feature from this unit is the presence of two 3-pin fan power plugs coming from inside the power supply. These power connectors are connected in parallel to the unit’s fan, so fans installed to these connectors will have their speed changing according to the power supply internal temperature. This is a really nice touch.
As expected, this unit has active PFC circuit, auto voltage selection and efficiency between 82% and 86%, according to the manufacturer. Let’s see if this is true during our tests.
The main motherboard cable uses a 20/24-pin connector and this unit comes with only one ATX12V connector. No EPS12V connector is available, and this may be a huge drawback for you. And since this unit has four video card cables, not having an EPS12V connector is simply inexcusable, as if you are going to use two high-end cards with two auxiliary power connector each, you will be using a high-end motherboard that requires an EPS12V power connector. Both Corsair VX450W and Antec EarthWatts 500 W come with an EPS12V connector, so the option for not having it was made by Arctic Cooling and not by Seasonic.
This power supply comes with six peripheral cables: Two cables with a 6-pin video card auxiliary connector each, two cables with a 6/8-pin video card auxiliary power connector each, one cable with six SATA power plugs and one cable with three standard peripheral power plugs and one floppy disk drive power plug.
The presence of four individual auxiliary video card power connectors is a really good thing, as you can install two high-end video cards in SLI or CrossFire modes without the need of adapters. On the other hand, they all use 20 AWG wires, which is not the best option. The manufacturer should have used 18 AWG wires. The use of thinner wires can make the voltage on the connectors to drop when under heavy load.
The use of only one cable containing all SATA power plugs is questionable, as depending on the size of your case you won’t be able to have your SATA optical drive installed on the top-most bay (the distance between the first and the last connectors isn’t enough).
Other wires are 18 AWG, which is the correct gauge to be used nowadays.
Now let’s take an in-depth look inside this power supply.
[nextpage title=”A Look Inside The Fusion 550RF”]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.
Figure 3: Overall look.
In Figure 4, you can see how the manufacturer added a “tunnel” in front of the fan in order to increase the airflow on the area between the switching transistors heatsink and the secondary heatsink. Not a bad idea at all.
Figure 4: “Wind tunnel.”
Figure 5: Overall look.
Figure 6: Overall look.
[nextpage title=”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.
The transient filtering stage from this power supply is flawless, coming with one extra X capacitor and one extra coil. The Y capacitors are after the rectification bridge and there is another X capacitor also there. This stage is identical to the one from Corsair VX450W and Antec EarthWatts 500 W.
Figure 7: Transient filtering stage.
Figure 8: Transient filtering stage.
Now let’s have a more detailed look inside Arctic Cooling Fusion 550RF.
[nextpage title=”Primary Analysis”]
On this page we will take an in-depth look at the primary stage of Fusion 550RF. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.
This power supply uses one GBU806 rectifying bridge in its primary stage, which can deliver up to 8 A (rated at 100° C). This is more than adequate rating for a 500 W-550 W power supply. The reason why is that at 115 V this unit would be able to pull up to 920 W from the power grid; assuming 80% efficiency, the bridge would allow this unit to deliver up to 736 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 component is located on the same heatsink as the switching transistors.
The active PFC circuit from this power supply uses two FQH18N50V2 power MOSFET transistors, which are capable of delivering up to 20 A at 25° C or 12.7 at 100° C in continuous mode, or up to 80 A in pulse mode.
Figure 9: Active PFC transistors and diode.
The electrolytic capacitor in charge of filtering the output from the PFC circuit is Japanese from Chemi-Con, which is great.
The PFC circuit is controlled by the omnipresent PFC/PWM controller CM6800, which is located on a small printed circuit board shown in Figure 10.
Figure 10: Active PFC and PWM combo controller.
In the switching section, another two FQH18N50V2 power MOSFET transistors in two-transistor forward configuration are used. The specs for these transistors are published above.
Figure 11: Rectifying bridge and switching transistors.
All components from the primary are identical to the ones used on Corsair VX450W and Antec EarthWatts 500 W.
[nextpage title=”Secondary Analysis”]
Arctic Cooling Fusion 550RF uses four Schottky rectifiers on its secondary.
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. Just as an exercise, we can assume a typical duty cycle of 30%. Of course the maximum current (and thus power) this line can really deliver will depend on other components, especially the coil.
+12 V rectification is done by two SBR30A50CT Schottky rectifiers, each one supporting up to 30 A (15 A per internal diode at 110° C), so we have a maximum theoretical current of 43 A (15 A x 2 / 0.70), which corresponds to 514 W.
The +5 V output is produced by one STPS30L30CT Schottky rectifier, which supports up to 30 A (15 A per internal diode) at 140° C. This translates into a maximum theoretical current of 21 A or 107 W.
Another STPS30L30CT is used to rectify the +3.3 V output, giving a maximum theoretical current of 21 A or 71 W for this output.
Figure 12: +3.3V, +5V and +12 V rectifiers.
The secondary is monitored by an HY510N integrated circuit, which is installed on a small daughterboard and provides some of the power supply protections, like under voltage (UVP) and over voltage (OVP).
Figure 13: Monitoring circuit.
This unit uses a tiny semiconductor thermal sensor, which is located on the solder side from the printed circuit board.
The electrolytic capacitors from the secondary are from OST, labeled at 105° C as usual.
All components from the secondary are identical to the ones used on Corsair VX450W and Antec EarthWatts 500 W, so we can clearly say that the reviewed power supply and these other two units are identical.
[nextpage title=”Power Distribution”]
In Figure 14, you can see the power supply label containing all the power specs.
Figure 14: Power supply label (pay attention to the “max 1 second” near “550 W”).
This power supply features two +12 V virtual rails distributed like this:
- +12V1 (solid yellow wire): All cables but the ATX12V and main motherboard cable.
- +12V2 (yellow with black stripe wire): ATX12V and main motherboard cable.
Now let’s see if this power supply can really deliver 550 W.
[nextpage title=”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 behav
ed under each load. In the table below we list the load patterns we used and the results for each load.
But since we knew beforehand that we were dealing with a 500 W power supply – and not a 550 W as one would assume from its label –, we considered 500 W for its maximum capacity and the tests present on this page reflect this.
For the 100% load test we used two patterns. The first one, test number five, we respected the limits printed on the power supply label (17 A maximum for each +12 V rail). To achieve this pattern, however, we had to configure the +12 V outputs with a current lower than we wanted, and increase current on +5 V and +3.3 V outputs to a value higher than we wanted. After testing the power supply with this pattern, we configured our load tester with the pattern described below as test six, increasing current on +12 V outputs and lowering current on +5 V and +3.3 V outputs, which is the standard we use on our tests.
+12V1 and +12V2 are the two inputs from our load tester, with +12V1 input connected to the power supply +12V1 and +12V2 rails and with +12V2 input connected to the power supply +12V2 rail.
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 | 4 A (48 W) | 7 A (84 W) | 11 A (132 W) | 14.5 A (174 W) | 17 A (204 W) | 18 A (216 W) |
| +12V2 | 3 A (36 W) | 7 A (84 W) | 10 A (120 W) | 14 A (168 W) | 17 A (204 W) | 18 A (216 W) |
| +5V | 1 A (5 W) | 2 A (10 W) | 4 A (20 W) | 5 A (25 W) | 9 A (45 W) | 6 A (30 W) |
| +3.3 V | 1 A (3.3 W) | 2 A (6.6 W) | 4 A (13.2 W) | 5 A (16.5 W) | 9 A (29.7 W) | 6 A (19.8 W) |
| +5VSB | 1 A (5 W) | 1 A (5 W) | 1.5 A (7.5 W) | 2 A (10 W) | 2.5 A (12.5 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) | 0.5 A (6 W) | 0.5 A (6 W) |
| Total | 101.8 W | 192.1 W | 292.8 W | 388.9 W | 488.6 W | 482.4 W |
| % Max Load | 20.4% | 38.4% | 58.6% | 77.8% | 97.7% | 96.5% |
| Room Temp. | 46.3° C | 45.9° C | 47.1° C | 47.3° C | 50.0° C | 50.0° C |
| PSU Temp. | 47.5° C | 47.4° C | 47.6° C | 47.8° C | 50.4° C | 48.7° C |
| Voltage Stability | Fail | Fail | Fail | Pass | Pass | Pass |
| Ripple and Noise | Pass | Pass | Pass | Pass | Pass | Pass |
| AC Power | 114 W | 214 W | 331 W | 453 W | 587 W | 578 W |
| Efficiency | 89.3% | 89.8% | 88.5% | 85.8% | 83.2% | 83.5% |
| Final Result | Fail | Fail | Fail | Pass | Pass | Pass |
Arctic Cooling 550RF achieved an excellent efficiency between 85.8% and 89.8% when we pulled up to 80% of its real wattage (500 W), i.e., up to 400 W. When we pulled 500 W efficiency dropped, but to 83%, which is still a very good result.
The problem, however, was that during tests one, two and three +12V voltages where at 10.8 V and thus below the minimum allowed (11.4 V). This is not good.
Noise and ripple on the other hand were at very good levels. During test number five we saw 45 mV at +12V1, 49 mV at +12V2, 20 mV at +5 V and 10.2 mV at +3.3 V. The maximum allowed values are 120 mV for the +12 V outputs and 50 mV for the +5 V and +3.3 V outputs and we always want to see noise at half of the maximum allowed or below that, feat accomplished by this unit. All values are peak-to-peak.
Figure 15: Noise level at +12V1 during test six (43.6 mV).
Figure 16: Noise level at +12V2 during test six (49.8 mV).
Figure 17: Noise level at +5 V during test six (16.4 mV).
Figure 18: Noise level at +3.3 V during test six (10 mV).
Now let’s see if we can pull even more power from Fusion 550RF.
[nextpage title=”Overload Tests”]
Before overloading power supplies we always test first if the over current protection (OCP) circuit is active and at what level it is configured. We configured current on the +12V2 input from our load tester to 1 A and increased current on the +12V2 input to 33 A and the power supply didn’t shut down. This means that either the OCP circuit is disabled or is configured at a value above 33 A. We don’t like this, especially when the label says that each +12V rail has a 17 A limit.
This unit, however, has other protections in action. Below you can see the maximum we could extract from this power supply. Above that, the power supply would shut down. As you can see we could pull up to 545 W from it, being “almost” a 550 W model. But even if we could pull 550 W from it, this wouldn’t make it a 550 W model: manufacturers usually leave a 10-20% safety margin. During this test noise levels where still low (51.6 mV for +12V1, 61.4 mV for +12V2, 19 mV for +5 V and 10.8 mV for +3.3 V). See how efficiency was still above 80%.
The voltage on +12V outputs where, however, at 11.6 V. While this is still inside the 5% margin set by the ATX standard (+12 V output can be between 11.4 V and 12.6 V), it was too close to the lower limit.
| Input | Maximum |
| +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 (12.5 W) |
| -12 V | 0.5 A (6 W) |
| Total | 544.9 W |
| % Max Load | 109% |
| Room Temp. | 48.4° C |
| PSU Temp. | 47.4° C |
| AC Power | 666 W |
| Efficiency | 81.8% |
[nextpage title=”Ma
in Specifications”]
Arctic Cooling 550RF power supply specs include:
- Nominal labeled power: 500 W continuous, 550 W peak (for one second)
- Measured maximum power: 544.9 W at 48.4° C.
- Labeled efficiency: Between 82% and 86%.
- Measured efficiency: Between 83% and 89% at 115 V.
- Active PFC: Yes.
- Modular Cabling System: No.
- Motherboard Power Connectors: One 20/24-pin connector and one ATX12V connector.
- Video Card Power Connectors: Two 6-pin connectors and two 6/8-pin connectors.
- Peripheral Power Connectors: Three in one cable.
- Floppy Disk Drive Power Connectors: One.
- SATA Power Connectors: Six in one cable.
- Protections: over current (OCP, tested and not working), over voltage (OVP, not tested), over power (OPP, tested and working) and short-circuit (SCP, tested and working).
- Warranty: Three years.
- More Information: https://www.arctic.ac
- Suggested retail price: USD 91.95 or € 63.95
[nextpage title=”Conclusions”]
Even though this power supply has four video card auxiliary connectors, it has enough flaws for us not to recommend it – even though internally it is identical to two other excellent power supplies we reviewed and recommend, Corsair VX450W and Antec EarthWatts 500 W.
The first one and most obvious is labeling the power supply with its peak power instead of labeling it with its continuous power. This is very deceiving and we couldn’t expect this from a Switzerland-based company. From our tests it is clear that Fusion RF550 is really a 500 W model. Even though we could pull up to 545 W model, this doesn’t make it a 545 W or 550 W model, because manufacturers must leave a 10-20% safety margin.
Second was the thinner 20 AWG wires used, the probable cause of the +12 V output being below the minimum allowed during some tests (10.8 V while the minimum allowed is 11.4 V).
Third, the absence of an EPS12V connector. This doesn’t make sense: since you can install two high-end video cards with two auxiliary power connectors each with this power supply, you will be probably using a high-end motherboard, which requires an EPS12V power connector.
Fourth, the limited number of peripheral power connectors (only three) and the fact that all SATA power connectors are installed on the same cable, making it almost impossible for you to install your optical unit on the top bay if you have a tall case.
On the positive side, we liked the fan power connectors coming from inside the power supply controlling the fan speeds according to the power supply internal temperature.
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