Final Thoughts and Conclusions

With the introduction of the FOCUS SGX series, Seasonic now has two SFX-L power supplies to offer small form-factor enthusiasts. And as we have come to expect from Seasonic, the overall performance was very good to excellent.

The voltage regulation for the three main outputs (+12V, +5V, and +3.3V) was excellent and easily exceeded Seasonic’s own claim of ±3%. The all important +12V output stayed within 1%. AC ripple and noise suppression was also very good staying well below the recommended guidelines. And the power supply features a good assortment of modular cables and delivers good efficiency, easily meeting the 80Plus Gold criteria.

In the past many SFX power supplies were very noisy due to a high-speed 80mm fan. But with a slightly lengthened chassis and a 120mm fan onboard the SGX-650 was silent to relatively quiet from low through mid-power outputs thanks to Seasonic’s Hybrid Silent Fan Control that allows silent, fanless operation below about 30% load.

We were a bit surprised to see the 650W max output power de-rated to 520W (80% laod) when the operating temperature exceeds 40°C. And even though a SFX to ATX adapter bracket is included, the modular cables are intentionally short for small form-factor builds and will likely be too short to use in a larger case.

The MSRP for the two Seasonic SGX Series power supplies is currently:

•    Seasonic FOCUS SGX-450 ($99.99 USD)
•    Seasonic FOCUS SGX-650 ($129.99 USD)

•    650W of Continuous DC output at up to 40°C
•    Easily meets 80 PLUS Gold certification criteria
•    Excellent voltage regulation (±2%) on the three primary outputs
•    Very good AC ripple and noise suppression
•    Quiet 120mm cooling fan with a fluid dynamic bearing (FDB)
•    Hybrid Silent Fan Control allows silent, fan-less operation at low power
•    Compact SFX-L chassis measures 125mm square
•    Good assortment of fully modular cables with (4) PCI-E connectors
•    All Japanese made capacitors for reliable operation
•    10-Year warranty

Minor Weaknesses:
•    Max output de-rated to 520W when operating above 40°C
•    Cables may be too short when used in a larger case via the SFX to ATX adapter

Seasonic FOCUS SGX-650 SFX-L Power Supply

Our thanks to Seasonic for sending us the SGX-650 PSU to review.

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