Seasonic FOCUS SGX-450 450W SFX-L PSU Review

Author:Paul Johnson

Editor:Kyle Bennett

Date: Monday , December 31, 2018

Seasonic is delving deeper into the small form factor end of the power supply pool with its new FOCUS SGX. The SGX-450 has a 125mm x 125mm footprint, is supplied with an ATX adapter bracket, is fully modular, carries Gold efficiency certification, and comes with Seasonic's rock solid 10 year warranty.

Build Quality

As we already know the FOCUS SGX-450 feature a single 120mm fan design like many other offerings on the market that has come to be the preferred standard for quiet cooling environments 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

From the exterior, today's FOCUS SGX-450 looks a lot like a miniaturized FOCUS PLUS unit. So, given the number of FOCUS PLUS units we have seen, much of the exterior build quality of this unit is going to sound familiar. Once more, the quality of the exterior seems to be excellent while the layout of the unit is typical of what we see with single overhead fan designs that have modular cables and APFC in the SFX-L form factor in a few previous examples from other vendors. When we look at the finishing touches, we do see a rather large change in the fan guard design which ditches the straight wire grill of other FOCUS branded units. After that though, the FOCUS+ branding and labeled modular interface are very familiar pieces as is the underlying textured black finish that seems to be very high quality. So, while smaller in dimension-ality, the FOCUS SGX-450 looks very sharp and well done which has been the usual occurrence for the FOCUS PLUS line.

The FOCUS SGX-450 comes in at a total length of ~4 7/8 inches while the cables come in at a length of ~13" to 18" to the first or only connector. Additionally, the cables are all the FlexForce style cables which are completely sleeved (obviously).

Internal Build Quality

Once we open the top of the FOCUS SGX-450 we, unsurprisingly, see a very small and rather cramped power supply that seems to be a fairly heavily modified design based on the design used in FOCUS units (most of this modification seems to be due to the capacity and much smaller enclosure we have here today). Starting with the fan, we see a Globe Fan manufactured FDB fan rated at 0.45A at 12v. Paired with this fan we once more see at least 5 heatsinks of various sizes. The topology used in this unit is again a LLC primary and a secondary where we have synchronous rectification with DC-DC VRMs for the minor rails. When we look at the back of PCB, we see that the soldering is very neat once more and Seasonic has done an excellent job with this aspect of the units build quality as always.

On the primary side of the FOCUS SGX-450 , we see that input filtering begins up on the housing with some X and Y capacitors on a PCB. The input filtering then trails onto the main PCB where we find that it is complete. The bridge rectifier is found next attached to one of the two primary side heatsinks. As we move around to the primary side proper, we find a coil along with the APFC power components on a heatsink which is on the edge of the main PCB. Behind this heatsink, we find the main input capacitor which is provided by Hitachi. This capacitor is rated at 400v 390uF 105C. Then, towards the center of the PCB, the switching transistors are found attached to the heatsink that the bridge rectifier is also attached to.

Moving over to the secondary side, we see small heatsinks for the secondary power components arranged between the large transformer in the center of the secondary side and the modular PCB. Scattered throughout this area is a mix of solid and standard electrolytics from Nippon Chemi-con. Up against the modular PCB, we see another add-in PCB which houses the DC-DC VRMs. This PCB is populated by a number of FPCAP solid capacitors. When we move over to look at the modular PCB itself, we see that the single layer PCB is generally cleanly constructed. On the front side of the modular PCB, we see a number of solid and standard capacitors that are once more provided by FCPAP and Nippon Chemi-con respectively.

Build Quality Summary

Rather unsurprisingly, the FOCUS SGX-450 represents another excellent product from Seasonic when it comes to build quality and gives us a lot to look forward too from these SFX-L units in general. While this unit is similar in a lot of ways to the previous FOCUS PLUS units, it is also different in a lot of ways (which is sort of obvious given the units diminutive size and all). The exterior of this unit features an overall fit and finish that seems to be very high quality as we have seen before. On top of that, it shares many of the styling queues with previous FOCUS PLUS units; differing only in the fan grill when it comes to relevant features. Pairing with that, we also see that the cables we get today are all FlexForce style cables which is a nice touch. The interior build quality follows along these lines as well as we see excellent execution and very good attention to detail. The component selection is again high quality as we see a Globe Fan FDB fan along with capacitors from Nippon Chemi-con (solid and standard), Hitachi (standard), and FPCAP (solid). All in all, today's FOCUS SGX-450 looks like a well put together unit that fits in with all the rest we have seen from Seasonic over the years. So, let's move on now to the load tests and see how this unit does there.