Seasonic G-Series: G-550 Power Supply Review

The Seasonic G Series PSU is here for review in its 550 watt capacity and it looks to be a return to basics for the company with this being basically a "no-frills" unit that has been released without much fanfare. But the basics for Seasonic usually outline what you truly need in a PSU; reliable clean power with a low sound profile.

continued...

Build Quality

As we already know the Seasonic G-550 features a single 120mm fan design that has come to be the preferred standard for quiet cooling environments, which Seasonic has been the longtime leader in, due to the ability to move a larger volume of air at slower speeds than a smaller diameter fan. While great for quiet computing environments the key criteria in our evaluation is whether or not the cooling solution is sufficient, not necessary it’s sound level or form factor.

External Build Quality

Article Image Article Image Article Image

Article Image Article Image

The exterior of the Seasonic G-550 is the one area where we can clearly see that this unit is not being positioned as a premium offering from Seasonic. While not bad, the exterior lacks a lot of the finishing touches that make the X-Series units appear to be higher end products. One of the key things contributing to this impression is the fact that this unit is only semi-modular rather than fully modular. We also see that the branding is a little less compete with no gold touches as we have seen before on the 80 Plus rated Gold rated X-Series units, but the new G-Series logo has some of it's own touches as it has blue under tones on the label. Otherwise, the unit is much like we have seen before with the form factor being dominated by the single 120mm over head fan.

Article Image Article Image

The Seasonic G-550 itself is ~6 1/2 inches long while the cables provide a serviceable length of ~17 to 24 inches to the first or only connector. The sleeving is a mix of the flat FlexForce style cables as well as standard sleeving with the standard sleeving being a bit short.

Internal Build Quality

Article Image Article Image Article Image

Article Image

Once we open the Seasonic G-550, we see a different layout than what we have been seeing in Seasonic’s X-Series units. The layout of the unit is mostly traditional with the topology being a resonant LLC primary with an odd synchronous rectification secondary and DC-DC VRMs for the minor rails. From the top, we see four heatsinks, all of which are on the small side as we have seen before from Seasonic in its very efficient designs. Paired with these heatsinks for cooling we see an ADDA fan rated at 0.33A at 12v. When we flip the PCB over, we see the typically neat soldering of Seasonic, a few less-than-great places but overall it is neatly done, as well as the 12v MOSFETs and 12v Schottky diodes.

Article Image Article Image Article Image

Article Image

The input filtering begins up on the housing itself and then trails onto the main PCB. After all is said and done the input filtering stage is complete with all required parts (and a few extra X and Y capacitors). Almost abutting the main heatsink on the primary side is a small heatsink that houses the bridge rectifier. The large heatsink that is on the edge of the main PCB houses the PFC power components. Towards the back edge of the main PCB, we see the main input capacitor which is provided by Nippon Chemi-con and is rated at 420v 390uF 105C. Between this capacitor and the actual edge of the PCB is an add-in PCB that houses the resonant and PFC controllers. Lastly, the heatsink that is towards the center of the unit houses the main switching transistors.

Article Image Article Image Article Image

Article Image

Moving over to the secondary we see a number of changes from what we have become used to seeing from the higher-end X-Series units. The big difference we see right away is the add-in PCB that is housing the DC-DC VRMs which is attached to a heatsink. Contained on this add in PCB, and spread around on the main PCB, we find a number of solid capacitors provided by Enesol. The standard electrolytics we find hanging around are provided by Nippon Chemi-con again. The other add-in PCB on this side of the power supply houses the protection circuitry. When we turn our attention to the modular interface, we see that it is generally clean with good soldering. There are a number of capacitors on the front of the PCB that will be stuck near the housing with no airflow and unfortunately these are standard electrolytics. Lastly, the wiring is well bundled and those wires which are fixed exit the housing through a wire guard and are sleeved all the way into the housing.

Build Quality Summary

The Seasonic G-550’s build quality is just a bit behind what we have seen from Seasonic’s flagship X-Series units for the most part. One area that makes this unit feel a bit lower-end is mostly aesthetic with the way Seasonic has trimmed the unit out and the fact that it is only semi-modular. When we move to the interior, we find a vastly different layout from what we have seen with the X-Series units we have been seeing so much of lately but the topology is still thoroughly modern and the components are generally high quality. The one interior issue which takes a bit away from this unit compared to some other Seasonic units is the inclusion of an ADDA fan over the higher-end Sanyo Denki’s that we have seen from time to time. The capacitor selection, however, is high quality with Nippon Chemi-con providing the standard electrolytics and Enesol providing the solid capacitors. Lastly, the actual integration is generally very clean with a good clean layout and a good soldering job. So, let’s move on to the load testing now.