The Seasonic Focus Plus Gold 750FX 750W PSU Review: SeaSonic Quality at Mainstream Pricesby E. Fylladitakis on May 16, 2019 10:00 AM EST
Despite its relatively high power output, SeaSonic managed to fit the Focus Plus Gold 750FX into a standard ATX 150 × 140 × 86 mm (W×D×H) chassis. The 140 mm deep body ensures that the Focus Plus Gold 750FX will fit in any ATX-compliant case, including Desktop HTPC and other compact designs. The sticker with the electrical specifications and certifications of the PSU can be found at the top side of the unit.
Although SeaSonic usually is very subtle when it comes to aesthetics, we can safely declare that the Focus Plus Gold 750FX is an exception. The designer clearly went out of their way to make this PSU aesthetically appealing beyond just a good paint job. At the bottom of the chassis, we find a unique fan grill with a golden badge at its center and grey accents surrounding the fan. Embossed geometric designs can be found on the left and right sides of the PSU, while the gold-accented company and series logos can be found on every side.
Besides the typical on/off switch and an AC cable receptacle, SeaSonic also placed a square locking switch on the rear side of the PSU. This switch can be used to enable the cooling fan’s hybrid control mode. Enabled by default, in hybrid mode the fan will turn on only when the unit’s load is high enough to require active cooling. Otherwise if hybrid mode is disabled, the fan’s speed will still be thermally controlled, but it will always run and never go completely fanless.
Meanwhile the front of the PSU is home to the connectors for the modular cables. SeaSonic did not color-code the connectors, but they have a basic legend printed on the chassis that indicates where each connector goes. PCI Express and CPU 12V cables share the same connectors. It is practically impossible for a user to insert a cable into the wrong connector, as each cable type has a different connector and the connectors are keyed.
The cooling fan under the fancy finger guard is the HA1225H12F-Z from Hong Hua. It appears visually simple but features a high-quality Fluid Dynamic Bearing (FDB) with a high life expectancy and promises relatively low noise levels. It has a theoretical rotational speed of 2200 RPM but is thermally controlled and should only actually reach those speeds if the PSU is highly stressed.
There is no need to verify the OEM of this unit as SeaSonic obviously is both the designer and the maker of this power supply. The interior of the unit is very tidy, shouting the obvious lack of wires between the main and the connector’s PCBs, which are joined together via a large copper bridge. The heatsinks are worryingly simple for a PSU of this power rating, suggesting that SeaSonic is very confident regarding its conversion efficiency.
A small PCB is soldered on the back of the AC cable receptacle, hosting a few parts of the filtering stage. The total filtering stage consists of four Y capacitors, two X capacitors, and two filtering inductors. A MOV is also present, as well as an IC that handles the discharging of the filtering capacitors (CM02X). Right after the filtering stage, two bridge rectifiers share the one and only high-density heatsink found in the unit.
The APFC circuit is textbook, with the active components on the thick, crude heatsink across the edge of the PCB. Nippon Chemi-Con supplies the single 400V/560μF capacitor that sits next to a decently-sized enclosed-type filtering coil.
A rare sight these days, the Focus Plus Gold 750FX sports four primary inversion side MOSFETs that form an LLC resonant full-bridge topology. On the other side, another four MOSFETs generate the single 12V line. The DC-to-DC converters for the 5V and 3.3V voltage lines can be seen on the moderately sized vertical PCB that has a heatsink hidden behind it. All of the secondary side capacitors, electrolytic and solid alike, are made by Nippon Chemi-Con.