Corsair VX550W vs. Corsair HX520W

We know Corsair's mid-range power supplies are some of the best in the industry, but what if we put their PSUs head to head? If you are set on a Corsair PSU, you will want to check this out. Which is the best 500w+ PSU for you?

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Load Testing

For those of you that are curious as to some of the reasoning and equipment behind our PSU testing program here at HardOCP, we have put together a living document that shares a lot of the behind the scenes of the program. The testing we are conducting today is exactly as described in that document and will begin with a range of loads tested at 120v input including our torture test and then move on to the same set of tests at 100v input but without the torture test.

120v Load Testing Results

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100v Load Testing Results

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Test #1 is equal to approximately 25% of the rated capacity of the Corsair VX550W at 45c. This makes Test #1 equal to 134w by loading the 12v rail to 8a, the 5v rail to 3a, the 3.3v rail to 2a, the +5vsb to 2a, and the -12v to 0.5a. The results of Test #1 at both 120v and 100v are good with all the DC output voltages remaining the same at both AC input voltages. The big difference is the unitآ’s efficiency is ~80% at 120v and ~79% at 100v but both values are certainly on the better end of the spectrum. At the same time the unit is exhausting at 48c even with the large 120mm fan employed here.

Test #2 is equal to approximately 50% of the rated capacity of the Corsair VX550W at 45c. This makes Test #2 equal to 244w by loading the 12v rail to 16a, the 5v rail to 5a, the 3.3v rail to 3a, the +5vsb to 2a, and the -12v to 0.5a. As Test #2 doubles the load we see an ever so slight drop in output voltages at both 120v and 100v. Much like Test #1 the only real difference between 120v and 100v tests is in the unitآ’s efficiency which is at a stellar ~84% at 120v and ~83% at 100v.

Test #3 is equal to approximately 75% of the rated capacity of the Corsair VX550W at 45c. This makes Test #3 equal to 405w by loading the 12v rail to 28a, the 5v rail to 7a, the 3.3v rail to 5a, the +5vsb to 2a, and the -12v to 0.5a. Test #3 sees the DC output voltages drop again ever so slightly with none moving more than 0.02v. At the same time the unitآ’s efficiency has dropped back to an extremely solid ~82% at both 120v and 100v with an exhaust temperature of 52c.

Test #4 is equal to approximately 100% of the rated capacity of the Corsair VX550W at 45c. This makes Test #4 equal to 520w by loading the 12v rail to 40a, the 5v rail to 3a, the 3.3v rail to 2a, the +5vsb to 2a, and the -12v to 0.5a. In the final regular test the only change in DC output voltage is the very slight dip on the 12v rail to 12.01v. The unitآ’s efficiency has dropped once more and now registers 81.25% at 120v and 80.74% at 100v with the exhaust peaking at 56c in the 100v test.

Torture Testing

The final component of our load testing involves our 8 hour torture test. This test is meant to simulate what gaming or hardware enthusiasts might encounter when they use their systems for extended periods of time under stressful conditions such as 3D gaming or long term stability testing and benchmarking. However though, we do not suggest using your power supply at 100% loads for extended periods of time and our torture test does reflect this. We load the PSU being tested to ~80% of its rated capacity for 8 hours at a temperature of 45c. This is outlined in our testing Methodology should you wish to have more information.

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Torture Test is equal to approximately 80% of the rated capacity of the Corsair VX550W at 45c. This makes Test #3 equal to 431w by loading the 12v rail to 29a, the 5v rail to 9a, the 3.3v rail to 6a, the +5vsb to 2a, and the -12v to 0.5a. The results of the Torture Test are very similar to those seen in the closely related Test #3 as we have seen a number of times previous for units that are able to finish the 8 hour run at 45c. None of the voltages dropped more than 0.02v from Test #3 levels while the unit was able to post an efficiency of 82.10% with an exhaust temperature of 55c.

Load Testing Summary

The VX550W's load testing results today are simply outstanding with voltage regulation that is some of the best we have seen to date. The 12v rail showed a drop of only 0.06v over the 40A load that was placed on it. At the same time the 5v and 3.3v rails showed even better performance; though the loads were lighter. If this was not impressive enough the units efficiency ranged from 79.76% to 84.14% at 120v and 78.82% to 83.28% at 100v during all of these tests. These are all excellent results and the unit was able to finish the Torture Test without batting an eyelash. The VX550W has certainly given the HX520W (as well as all other products in this output class) a very high standard to meet.

Transient Testing

The Transient Testing portion of this review marks the first revision to our living testing methodology. Readers can read more about this inclusion in our testing here in our methodology section, but briefly we will be examining the response of the power supply to a short duration load such as a RAID array spinning up or load change due to power draw from video cards etc. Ideally we would not see a deflection from the baseline voltage output when this occurs but that is simply not the case for the majority. We will be using the ATX12v specification for transient response as a guide.

The Transient Load Tester adds an additional 9.25A to the 12v rail for 10ms and an additional 3.75A to the 5v rail for 10ms at 25% total load and 50% total load.

Loaded/Unloaded

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12v/5v

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Test #1 is equal to approximately 25% of the rated capacity of the Corsair VX550W at 45c. This makes Test #1 equal to 134w by loading the 12v rail to 8a, the 5v rail to 3a, the 3.3v rail to 2a, the +5vsb to 2a, and the -12v to 0.5a before the addition of the transient load. The results of Test #1 show a peak change of ~200mV when the 12v rail is loaded and ~120mV change when the 5v rail is loaded. During the 12v load an unloaded 5v rail shows a peak change of ~140mV.

Loaded/Unloaded

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12v/5v

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Test #2 is equal to approximately 50% of the rated capacity of the Corsair VX550W at 45c. This makes Test #2 equal to 244w by loading the 12v rail to 16a, the 5v rail to 5a, the 3.3v rail to 3a, the +5vsb to 2a, and the -12v to 0.5a before the addition of the transient load. The results of Test #2 show a peak change of ~200mV when the 12v rail is loaded and ~120mV change when the 5v rail is loaded. During the 12v load an unloaded 5v rail shows a peak change of ~40mV.

Transient Load Testing Summary

The results of the Transient Testing for this unit are good. The 12v rail showed a peak change of ~200mV in both Test #1 and Test #2. At the same time the 5v rail had a peak change of 120mV in both Test #1 and Test #2 as well with the largest induced change by the 12v load occurring during Test #1 when it hit ~140mV. While the 12v changes may seem large in magnitude it is important to remember that the percentage of the units 12v capacity that the Transient Test represents for these lower capacity units is much higher than for the 1000w units on the market and as such the results are not directly comparable but are in line with what we have seen on other good ~500w power supplies to date. As such the unit passes the Transient Test with no reservations as its voltage output never really even approached the ATX12v limitations.