OCZ ZS Series 550W (Page 4 of 4) | Reports

Page 4 - Minor Tests and Conclusion

Power supplies are interesting products -- because often, reviews of products in this category are conducted and tested in methods that make it difficult to distinguish one power supply from another. Many aspects have to be taken into consideration -- of which certain criteria consists of efficiency, noise, power ripples, and of course the ability to pull out the rated specifications. Because many cannot afford such equipment to obtain results regarding those aspects, articles covering power supplies often come out with less than adequate and acceptable information. As this is a product report -- not a review -- what we are doing is a close examination of the power supply, and the internal hardware and build. But what we can do for you is do some minor testing with the results we can present to you with, and let other review sites with professional equipment show you the actual test results. We're not going to try to BS you by installing the power supply into the latest gaming rig and try to take readings from that, as this is not even remotely the correct way to test power supply units. We understand that many websites do that as a means of load testing, but the results, even if you use an oscilloscope and multimeter at each output location, it is not sufficient, nor does it accurately reflect the performance of the power supply.

Using our power supply tester which exerts minimum load on the power supply, the initial power consumption was 13W. It has the same initial power consumption as both the NZXT HALE90 750W and SilverStone Strider Plus ST75F-P 750W, as they both also rated in at 13W. Although this is not the lowest we have seen, this is well acceptable and from independent reviews from websites with professional load testing equipment showed excellent efficiency, voltage regulation, and ripple across the board -- right up to its rated wattage. It is also shown to hit the 80 PLUS Bronze mark as advertised as well.

The voltages with minimal load are very accurate and centered on range. A basic requirement of all good PSUs is to deliver the right voltages through the rails at minimal load, or there could be problems when using it in the first place. The PG (Power Good) measurement is also quite good at 300ms, which is about the average. I am actually surprised by how each voltage are spot on from the beginning, as I have never seen this happen before. Nevertheless, it is definitely a good thing.

Active power correction is important to correct AC load line loss. In AC power, there are three components to it; as there is a phase difference between current and voltage. This makes up the power triangle, which consists of the following: Average usable power (P, measured in watts), reactive power (Q, denoted as VA-R), and total power (S, written as VA). While they all have the same physical units, it is not the same thing as aforementioned. What we want is the average usable power -- with as little wasted reactive power as possible. The total power provided over the AC line is the magnitude of the two combined (sqrt(P^2+Q^2)). Power factor can then be easily calculated by P/S. The ideal value is 1.00, and this is where active PFC comes in. A nominal load of about 170W (~30%) on the OCZ ZS Series 550W had the power factor between 0.94 and 0.96. As the load increases, the PF should move closer to 0.99.

When it comes to noise, the OCZ ZS Series 550W is commendably quiet. When under regular load, the OCZ ZS Series 550W is nearly silent. The Globe Fan RL4Z B1352512M runs smoothly, and produces very little noise. Although this is all quite subjective, it is easily one of the quietest components in my test system. On a scale from 0-10 where 0 is silent and 10 is loudest, I would say the OCZ ZS Series 550W would be about 2.5/10 under normal load conditions. However, when it reaches over 50-60% of its maximum load, the noise does increase, since the fan needs to speed up to meet the task of dissipating more heat -- as with all intelligent cooling systems. At the end of the day, the OCZ ZS Series 550W definitely will not be the loudest component in most systems, since with increased load, there is bound to be more heat in the chassis itself. In turn, other fans in the system will need to respond to the extra heat as well. The OCZ ZS series 550W is certainly one of the quieter power supplies I have tested.

OCZ provided this product to APH Networks to facilitate this report.

Overall the OCZ ZS Series 550W is an excellent power supply for its intended market, with low noise and decent performance as tested by our affiliates with professional load testing equipment. It is hard not to recommend the OCZ ZS Series 550W for users needing a quality power supply. Retailing around $60 after MIR at time of press, it packs everything you need and delivers what is promised.

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Page Index
1. Introduction, Packaging, Specifications
2. Physical Look - Outside
3. Physical Look - Inside
4. Minor Tests and Conclusion