Seasonic FOCUS SGX-650 650W (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 must 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 are not going to try to create useless test results 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 9W as measured by our wall meter unit -- indicating that the basic load-free power consumption of the power supply was very good. Independent reviews from websites with professional load testing equipment showed the Seasonic FOCUS SGX-650 650W delivered very good efficiency and excellent voltage regulation and ripple across all rails. This is an 80 Plus Gold certified power supply unit and is very similar to the Seasonic FOCUS Plus 850 Gold 850W and NZXT E850 850W we previously reviewed.

Voltages with minimal load are generally accurate, which is a basic requirement of power supplies out of the box. In this situation, all are within 2%. The PG (Power Good) delay seems to be well within its rated range and general power supply standard of 360ms.

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 save 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 200W (30.8%) on the Seasonic FOCUS SGX-650 650W had the power factor at 0.99. This is excellent as expected.

The Seasonic FOCUS SGX-650 650W is silent to very quiet power supply, depending on the amount of power being drawn. Under idle level loads (Less than approximately 40%), the FOCUS SGX-650 is inaudible, because the fan is shut off completely. Under moderate to high loads (Above 30%), the FOCUS SGX-650 650W is very reasonably low noise. Personally, I found the Globe S1201512HB to be a decent fan acoustically. While this is very subjective, I am quite a picky person on noise. On a scale from 0 to 10 where 0 is silent and 10 is the loudest, I would rate the Seasonic FOCUS SGX-650 650W to be at 0.0/10 when the fan is off, because, well, the fan is off. Above that, I would peg it at 3.0/10 acoustically under moderate loads, because the fan does not spin that fast. The fan is acceptably quiet even at full speed. If you are a silent PC enthusiast, the Seasonic FOCUS SGX-650 650W is a great choice for small form factor systems.

Seasonic provided this product to APH Networks for the purpose of evaluation.

Built on the same excellent FOCUS Plus Gold platform as the Seasonic FOCUS Plus 850 Gold 850W, the FOCUS SGX-650 650W is an SFX-L power supply that delivered very good efficiency and excellent voltage regulation and ripple across all rails according to our affiliates with professional load testing equipment. Seasonic is known for their impeccable quality and reliability, but in case you are worried, they back it up with a decade-long warranty period. This high performance SFX-L PSU is also fully loaded with modular cables, a mega 120mm fan, and hybrid fan control. For about $125 at press time, the Seasonic FOCUS SGX-650 650W is an excellent choice to power up your next small form factor PC.

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