Seasonic Focus SGX 650W SFX-L PSU Review: Reliable Power, Tiny Form Factor

Specifications and Part Analysis

The Seasonic Focus SGX 650W offers high overall performance and quiet operation at light and medium loads, of up to 340W. The competition in the small form factor SFX-L category hasn't been heated up yet and we are still waiting for Super Flower to release its highly anticipating small factor platform. Nevertheless, there are still some worthy opponents which belong to the smaller, in dimensions, SFX category with the Corsair SF600 having identical performance with the SSR-650SGX but plenty of noise output with high loads on the minor rails. If you are out for an SFX-L unit with 650W capacity and a fair price ($122 / £139), the SSR-650SGX should be among the top places in your list. Another strong advantage of this product is the ten-year warranty, which is the longest in this category.

Seasonic has finally entered the small form factor PSU market with its new SGX line, which currently consists of two models with 500W and 650W capacities. Both of them follow the SFX-L form factor and target users that need a good power supply but don't want to spend a fortune to get it. Usually the smaller a PSU the higher its price, so to be more competitive, Seasonic didn't equip the SGX with exotic features, like ETA-A+ or 80 PLUS Titanium/Platinum efficiency, which would significantly affect the production cost.

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In this review we will take a look at the SSR-650SGX which is the strongest of the line with 650W max power, as its model number implies. This is a fully modular unit with a single +12V rail and a 120mm Fluid Dynamic Bearing fan. The impressive fact in this product is the ten-year warranty. Currently no other SFX-L or SFX unit is covered by such a long warranty, with Corsair's and EVGA's high-end SFX offerings being at seven-years. Personally I am not a fan of huge warranty periods since on the long run they can create problems not only to the brands that offer them but to the consumers as well, in case the RMA cost gets increased (hence this cost will have to be moved to the consumers somehow). Nonetheless, known brands like Seasonic, Corsair and EVGA wouldn't offer such long warranties, if they weren't extra sure that their products can outlive them.

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Specifications

Power Specifications

Cables & Connectors

This is a fully modular power supply. The number of PCIe connectors is adequate, given the 650W capacity, but the single EPS can create compatibility problems with some high-end mainboards. Ideally there should be two EPS connectors.

All cables are short since this unit is destined for a small chassis, but the distance between the peripheral connectors is large enough to cover all usage scenarios. Finally, it is nice to see clean, from in-line caps, cables since those caps make them bulky, hence cable rooting/management tasks become harder.

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Component Analysis

We strongly encourage you to a look at our PSUs 101 article, which provides valuable information about PSUs and their operation, allowing you to better understand the components we're about to discuss.

This is a new Seasonic platform featuring a half-bridge topology on the primary side which is enhanced by an LLC resonant converter, for restricted switching losses. On the secondary side, a synchronous rectification scheme is utilized for the +12V rail, while the minor rails are generated by a couple of DC-DC converters. The latter are hosted in the same PCB.

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The quality of the parts that Seasonic uses is top-notch. All filtering caps are provided by Japanese manufacturers (Rubycon, Chemi-Con, Nichicon and FPCAP) and besides electrolytic caps, a large number of polymers is also used. Lastly, the cooling fan measures 120mm; it is provided by Globe fan and uses a fluid dynamic bearing which has a long lifetime.

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