Seasonic PRIME 750W Gold Power Supply Review

Author:Paul Johnson

Editor:Kyle Bennett

Date: Wednesday, February 28, 2018

Seasonic has been on point with its PRIME power supplies lately on the Titanium and Platinum spectrum. Funny that a "Gold" efficiency PSU from Seasonic seems like a "low end" product, but rest assured, it seems that Seasonic is incapable of producing anything that is low-end now days. Is its new 750 watt PRIME Gold, [H] Gold?

Build Quality

As we already know the PRIME 750W Gold features a 135mm fan design. 135mm fans are in the same vein as 120mm fans in that they can provide for quiet cooling environments due to the ability to move a larger volume of air at slower speeds than a smaller diameter fan. The 135mm fan is about the largest diameter fan we are likely to see in ATX power supplies given the physical constraints of the form factor. 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

The external build quality of the PRIME 750W Gold is just about identical to the PRIME 1000W Gold. As such, the external build quality is excellent overall. When we look at some of the details we see that the accent color is Gold to match the position of this unit in the PRIME lineup. We also see a layout that is typical for single overhead fan designs that have modular cables and APFC. When we flip around and look at the sides of the unit, we again see the louvers or cutouts for allowing airflow along with the PRIME Gold and Seasonic silk screening. The front of the unit houses the modular interface with the various connectors outlined and labeled. The rear of the unit is nothing special, though we do find the fan switch back here once more. Lastly, the finish is high quality so it should be as durable as previous Seasonic offerings.

The PRIME 750W Gold comes in at a total length of ~6 3/4 inches while the cables come in at a length of ~18" to 27" to the first or only connector. Additionally, the cables are all sleeved in black mesh, which is very close to being complete, or are the FlexForce style cables which are completely sleeved.

Internal Build Quality

Once we open the top of the PRIME 750W Gold, we see a sight that is becoming rather familiar to us with the Seasonic PRIME units. Starting with the fan, we see a Hong Hua FDB fan rated at 0.5A at 12v (as was the case with the PRIME 1000W Gold) and it is paired with 4 or 5 heatsinks. The topology again features a full bridge resonant LLC primary and, on the secondary, we have synchronous rectification and DC-DC VRMs for the minor rails. When we look at the back of PCB, we see the 12v MOSFETs and soldering that is very neat once more.

Starting on the primary side, the PRIME 750W Gold's input filtering begins like the other PRIME units we have seen up on the housing itself with a PCB in a metal housing (but not a self contained can). This housing contains X capacitors, Y capacitors, and a coil. The input filtering then trails onto the main PCB where we find that it is complete. The bridge rectifiers are found next sandwiching a small aluminum heatsink. As we move around to the primary side proper, we find a coil along with the APFC power components on a heatsink. Behind this heatsink we find the main input capacitors which are provided by Nippon Chemi-con. These capacitors are rated at 400v 270uF 105C each. Besides these capacitors, we also see the main switchers attached to the heatsink towards the center of the PCB once more.

On the "secondary side," we see the same general design we have seen in all of the other PRIME units (including the PRIME 1000W Gold) we have reviewed. Once more, we see what looks like a small heatsink that is actually two heatsinks bridged by a screwed in aluminum piece to make them one unit. These heatsinks are used for helping to cool the 12v MOSFETS and these components also use the case housing as part of the overall cooling scheme as they are mounted on the rear of the main PCB. Next to this, we see the DC-DC VRMs behind the input capacitors. These VRMs are housed on an add-in PCB. Populating this PCB are some solid capacitors from both FPCAP and Nippon Chemi-con much like the rest of the secondary side of this unit. Additionally, throughout the secondary, we see a number of Nippon Chemi-con standard capacitors as well. Moving over to the modular PCB , we see that the modular PCB is very well constructed with very clean soldering. On the connector side, we see a number of solid capacitors here provided by FPCAP and some electrolytics from Nippon Chemi-con. Interestingly, as with the PRIME 1000W Gold, there are several positions screened for capacitors that are not populated today.

Build Quality Summary

Today's PRIME 750W Gold is, as we would expect given all of the previous PRIME units we have seen, excellent overall when it comes to the unit's build quality. The exterior is, once more, very well executed if a bit understated. The overall look is professional and sophisticated but a bit more subdued than what we get from the Titanium models due to the different color scheme. Moving to the interior of the PRIME 750W Gold, we again see a very familiar design and we see excellent build quality to match. From component placement to soldering and beyond the attention to detail is outstanding again today. The component selection is well matched to this integration effort, once more, as we see a Hong Hua FDB fan along with capacitors from Nippon Chemi-con (solid and standard) and FPCAP (solid). All in all again, the PRIME 750W Gold is starting off in excellent shape today much like its predecessors. So, let's move on our load tests and see if this unit performs likes its predecessors!