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 minimal load on the power supply, the initial consumption was 5W. Measured using our wall meter, this basic load-free power consumption of the OCZ ZT Series 650W is one of the lowest we have seen at our APH Networks labs. The OCZ ZT Series 650W power supply is among the lowest wattage power supply units along with the Thermaltake Litepower 450W, so we can safely say that such a low minimum draw power is understandable. For your reference, the Thermaltake Litepower 450W had an initial consumption of 7W. The OCZ ZT Series 650W is a 80+ Bronze Certified power supply, and it is reported from our affiliates with professional load testing equipment that the power supply lives up to its 80+ Bronze Certification.
Voltages with minimal load are generally accurate, which is a basic requirement of power supplies out of the box. The PG (Power Good) delay seems to be decently well within its rated range and general power supply standard of 389ms.
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. Under nominal loads, the power factor value for the OCZ ZT Series 650W shifted between 0.98-0.99, but stayed generally at 0.99, indicating that the active PFC function is working correctly.
When it comes down to fan noise, the OCZ ZT Series 650W does a very good job staying stealthy. When under load, the power supply remains fairly unnoticeable, and is still quieter than my case fans. On a scale from 0-10 where 0 is silent and 10 is the loudest, I would rate the OCZ ZT Series 650W at 2.0/10 acoustically under nominal loads. The power supply only gets some turbulence noise when the fan speeds up, but under idle conditions, you would only hear some noise when you stick your ear within close proximity.
OCZ provided this product to APH Networks to facilitate this report.
Overall, the OCZ ZT Series 650W power supply is a very decent fully modular mid-range PSU only for about $90 after rebate at press time. There is nothing much to complain about for something in this market niche. It performs well according to our affiliates with professional load testing equipment, but we are not sure how reliable Great Wall PSUs are in the long run.
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Page Index
1. Introduction, Packaging, Specifications
2. Physical Look - Outside
3. Physical Look - Inside
4. Minor Tests and Conclusion
