New prototype of Seasonic S12G 550 W: will the OPP work this time?


Back in April, I previously reviewed the Seasonic S12G 550 W (SSR-550RT). The unit we’ll be looking at today is nearly identical, so there’s no need to go over all the details again. To familiarize yourself with this model, I suggest you check out the full review to get all the information. The purpose of this article is only to cover the minor changes in the current revision of it. To recap, in the previous review I stated that this unit was not the first of this particular platform to come into my possession, and all of them so far have performed in the same way: Average voltage regulation, very bad ripple suppression, and they all started burning during combined overloading tests.


I’ve been in consultation with regard to my results with a Seasonic representative, and my findings thereof based on the improvements in the design of the Antec TruePower Classic 550 W (which is also based on the same Seasonic model). In that unit, I replaced the burned diode rectifiers with ones that have a 50 % better rating, and with that change, the unit’s overload protection did indeed kick in and cut off the power before the rectifiers could be pushed too far again. Based on this finding, Seasonic provided me with a new prototype which doesn’t exhibit the same problem as that earlier revision model, except that their fix was different than my own, as they simply did not install the rectifiers at all. It also seems to me that they possibly changed some of the surface-mount components on the underside of the board to adapt the driving circuitry for this change.


The second obvious change with this newly-revised unit is the use of different fan, namely the Hong Hua HA1225M12F-Z. It’s the same model that Seasonic uses in their Snow Silent power supplies, and it has maximum RPM of 2050 (150 RPM less than the original). It has a fluid bearing which should also lessen the overall noise. Later units with a manufacturing date of sometime during this summer or after are equipped with this new fan rather than the previous dual ball-bearing Jamicon model. So it seems that Seasonic got the message loud and clear that their previous units were too noisy.


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