Seasonic S12G 550 W: the cheapest 80 PLUS Gold unit with quality components?

Conclusion and evaluation

The Seasonic S12G 550 W (SSR-550RT) passed the combined and crossload testing in accordance with ATX specification so according to my evaluation methodology, it deserves its evaluation. On the bright side, as other units of this and similar platforms from Seasonic, it has quite good efficiency of over 90 % (but not with sub-100 watt load), uses only high-quality capacitors and on top, has quite long warranty with reasonable price. Oh and there are some fancy belts for your cable management in a computer case.

That’s about it. As in other units with the same semi-synchronous rectification, the over-power protection is set so high the SBR10U45 rectifiers burned once again. This is a third burned unit of Seasonic origin. While it happens under a somewhat specific scenario, it is not so specific it could not happen in real world so this is definitely not so good for a high-end unit. Good news is, Seasonic is working on this problem; for the units already on the market, be careful with your heavy overclocking or mining ;-)

Another problem with the series is worse voltage regulation especially for +3.3 V rail and −12 V rail, wich also has a very tight OCP limit. Especially the +3.3 V regulation constantly keeps me wondering how that is possible when the unit has DC-DC modules and is not depending on group regulation. Even worse problem is high ripple from the units high-frequency ripple interference. And the latest, well-known problem of Seasonic’s units, they are somewhat loud with fans spinning much faster than necessary, up to 100% speed for full load. This has been easily noticeable even next to my very loud load tester’s own cooling. While I understand why Seasonic is setting the cooling as it is, the fact remains there are competitive high-quality built units on the market which are not only quieter, but have warranty of similar length and often with tighter voltage regulation and ripple supression.

On the other hand, one fact goes for Seasonic too. For the informed buyer, this is not so much of an advantage because s/he knows exactly what is the best choice at the time, but for unaware buyers, Seasonic really has more or less constant quality over time (this year Seasonic celebrates 40 years in business), at least for the retail models, and you will not find yourself with some PoS no matter what you pick. This is a problem for many rebranders who switch OEM suppliers with each model – one is good, one is terrible.

Excellent example is Silverstone Strider Essential Series 600 W versus SFX Series 450 W. One is so bad it does not even comply with ATX standard, the other is so good it got a medal from me. But the SFX Series 600 W already has bad chinese c(r)apacitors. See the problem? You can more or less rely on Seasonic as a brand though it sometimes has slightly worse units, sometimes slightly better units, but never really bad units. You cannot have the same trust with many many other companies.

So the evaluation of the Seasonic S12G 550 W as high-end unit is as follows:

• components used: −1 p. (− for the lack of saver technology, − for non-working OPP, − for not high-enough component overrating, − for thinner wires)
• built quality: 8 p. (− for worse soldering)
• voltage regulation: −7 p. (− for combined loading, − for crossloading)
• ripple: −2 p. (− for combined loading, − for crossloading)
• efficiency: 14 p. (+ for higher efficiency)
• price: 13 p. (+ for lower price per watt)
• others: −7 p. (− for burning, + longer warranty, + for extra equipment)

Pros	+  high efficiency +  high-quality capacitors +  good build quality +  long warranty +  good price
Cons	− high ripple, under overload even out of spec − worse voltage regulation − faster and noisier fan than necessary − OPP set too high for underrated components, unit may burn
Be aware of…	/?\ overloading

Thanks

I thank the Partis company for lending the Seasonic S12G 550W. Discuss the article in our forums!

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