RelaxedTech Logo

Seasonic Focus SGX 650W Gold PSU Review: An SFX-L PSU With Seasonic Quality

Author: HP   Date:


Seasonic Focus SGX 650W Gold PSU Review

Seasonic recently announced a new naming initiative for their products called OneSeasonic which aims to streamline the company's product naming for simplicity and easier recognition. A few weeks ago I had the pleasure to interview Kevin Hu, Seasonic's product manager, and ask him some questions about the OneSeasonic initiative, and the current and future state of the power supply industry. Head over here if you are interested in reading my interview with Kevin Hu.

Early this year Seasonic entered the small-form-factor (SFF) market with their Focus SGX PSU line which is available in 80+ Gold efficiency and consists of three models ranging in capacity from 450W, 500W and up to 650W. Being an 80+ Gold certified PSU means it guarantees greater than 87%, 90% and 87% efficiency at 20%, 50% and 100% operating loads, respectively. The Focus SGX line is fully modular and comes in the SFX-L form-factor and features an impressive 10 years warranty. In my interview with Kevin, he mentions that Seasonic is working on developing an SFX line which I am really excited about.

Seasonic ships the Focus SGX with an SFX to ATX adapter which can be used to mount the PSU not only in an SFF case, but also in a standard ATX case. It comes with a silent Fluid Dynamic Bearing (FDB) 120mm fan with the ability to run in fanless mode. Seasonic's Focus SGX measures 125 mm in both length and width which allows it to fit into various sized computer cases.

Pricing & Warranty

You can find the Focus SGX 650W for $120 on Newegg which in my opinion is well-priced. On Amazon, it is about $2-5 cheaper compared to other fully modular SFX/SFX-L Gold PSUs from EVGA (SuperNOVA 650W GM / $125), Corsair (SF600W / $122), and SilverStone (SX600-G / $124). The $120 price-tag is a fair price for a PSU of this caliber in my opinion because you are getting a high build quality power supply with a hybrid fan control, an SFX-to-ATX adapter, 10 years of warranty, and is fully modular.

ManufactureFully Modular Gold SFXPrice (Amazon)WarrantyFan
EVGASuperNOVA 650GM$1257Y92mm

There are only a few companies that provide 10 year warranties on their power supplies and Seasonic is one of them. The majority of the manufactures offer 5 year warranties so this shows Seasonic's commitment to their PSU quality and longevity. Corsair's SF PSUs and EVGA's SuperNova PSUs come with a 7 year warranty while SilverStone's SX PSUs come with just a 3 year warranty. Seasonic's 10 years warranty makes me feel confident in the quality of the power supply.


Seasonic Focus SGX 650W
Max. DC Output650W
Over Voltage ProtectionYes
Weight4.8 lbs
Efficiency LevelETA-A
Form FactorIntel SFX 12 V / ATX 12 V
Dimensions125 mm (L) x 125 mm (W) x 63.5 mm (H)
Fan Size120 mm
Fan ControlPremium Hybrid Fan Control
Fan BearingFluid Dynamic Bearing
Life Expectancy50,000 hours at 40 °C, 15 % - 65 % RH
ModularityFully Modular
Cable typeFlat black cables
Operating Temperature0 - 50 °C (derating from 100 % to 80 % from 40 °C to 50 °C)
MTBF @ 25 °C, excl. fan100,000 hours
AC InputFull Range
ProtectionOPP, OVP, UVP, OCP, OTP, SCP
Safety and EMCcTUVus, TUV, CB, CCC, BSMI, EAC, CE
Environmental ComplianceEnergy Star, RoHS, WEEE, ErP Lot 6, REACH
Warranty10 Years
Voltage100 V - 240 V
Current9 - 4.5 A
Frequency50 Hz - 60 Hz
Load Range
Rail+3.3V+5V+12V-12 V+5 VSB
Max.(Amps)20 A20 A54 A0.3 A3 A
Max.(Power)100 W648 W3.6 W15 W
Total Continuous Power650 W


Seasonic Focus SGX 650W packaging

Seasonic ships the Focus SGX 650W Gold in a simple but elegant box. Looking at the front of the box, we see the Seasonic logo on the top left corner followed by the 'Focus SGX 650W Gold' text in the center and '10 Years Warranty' in the bottom right corner.

On the back, you will see a list of the features such as the 80-Plus gold certified, tight voltage regulation, 120mm fluid dynamic bearing fan, SFX to ATX adapter, cable-free connection, fully modular cabling design, compact SFX-L size and 10 years warranty. Size-wise, it is 125mm wide, 63.5mm tall and 125mm long and weighs 4.80 lbs.

Seasonic Focus SGX 650W box

The Focus SGX 650W is protected by two high density foams as shock absorbent to prevent any accidental damages during shipping. Inside the box you will find a set of Velcro straps, mounting screws, an SFX to ATX adapter, an AC power cord, a user manual and a bundle of modular flat black cables in a separate cloth bag. The user manual has all the information you need to know about the power supply such as how to set up your power supply and basic troubleshooting. Overall, the packaging is top notch just as you would expect from Seasonic.

The power supply is enclosed inside a cloth bag that gives it a nice premium feel to the overall product. Most manufactures package their power supplies in plastic bags so it's nice to see Seasonic go the extra mile with their packaging. You can tell that Seasonic takes packaging very seriously which is something that many companies take for granted.

Seasonic Focus SGX 650W cables

Here we have the fully modular flat black cables that are of ample length for all towers. The cables are not sleeved but they are flat so they offer great flexibility for tight folding and routing.

ConnectorConnector countCable countCable
Main Power (24/20 pins)11350 mm
CPU (8/4 pins)11400 mm
PCIe (8/6 pins)42400 mm + 100 mm
SATA62300 mm + 200 mm + 100 mm
Molex (4 pins)31300 mm + 200 mm + 200 mm
Molex Adapter11101 mm


The Focus SGX 650W sports a fully modular design which allows you to use only the cables you need thus helping improve case airflow and eliminating unnecessary wires and reducing clutter. Seasonic is using high-quality Japanese brand capacitors that ensure long-term reliability and all of the connectors are gold plated to maximize electrical transfer. The included SFX-to-ATX adapter might come in handy if you need to mount the PSU in an ATX case to reserve more space for airflow.

Seasonic Focus SGX 650W Hybrid Fan Control

Seasonic has equipped the Focus SGX with a 120mm Fluid Dynamic Bearing (FDB) fan which is a high quality fan that is extremely reliable and generates considerably less operating noise and heat than ball bearing fans. The fan is always enabled and has the ability to run in three operational stages: Fanless Mode, Silent Mode, and Cooling Mode. Based on the internal temperature of the PSU, the fan automatically switches between the different modes and it can turn off for silent operation if the loading condition is below 30%. I would have really liked for Seasonic to have included a fan switch at the back of the power supply like they do with the Focus Plus series because it allows users to manually set the fan mode.

Seasonic's Focus SGX series feature a tight voltage regulation which helps significantly with stability. When your computer is running, the current power draw can suddenly change for the CPU or GPU load and when this happens, the less change in voltage, the better because it results in better stability for the computer. Cheap power supplies do not handle voltage regulation very well, and can often damage the components of your computer.

Seasonic has also implemented a cable-free connection design solution where instead of cables, the back panel and the PCB are connected by a copper plate. This lowers the chance of production errors during manual insertion and also improves power efficiency.

Seasonic Focus SGX 650W Gold Review

Generally speaking, a good PSU is rated for 50°C operating temperature but the majority of them are normally rated for 40°C because it is a difficult standard to meet for most manufacturers. Something to keep in mind about the Focus SGX 650W is that Seasonic rates the operating temperature up to 50°C but only when the PSU load is 80% or less and derates it to 40°C when the PSU load exceeds 80%.

Build Quality

Seasonic Focus SGX 650W Build Quality

The top cover can be removed by unscrewing the four screws but keep in mind that removing the top cover voids the warranty so you lose the 10 years guaranteed warranty by the manufacturer. The first thing you will notice once the top cover is removed is the clean layout and the cable-free connection design of the power supply. All connections travel through the PCB which helps with improving output power quality. The integration and soldering quality is excellent just as you would expect from Seasonic.

Seasonic is using all high quality Japanese capacitors throughout the build. Japanese manufacturers such as Nippon Chemi-Con are known for making excellent capacitors and have a reputation for excellent quality control and are also said to use a refined electrolyte with better sealing capacity that are more resilient to higher temperatures. Both the primary and secondary stages are using high grade 105°C Japanese capacitors.

Seasonic Focus SGX 650W transistors

You will notice that Seasonic has placed some heatsinks in many key areas to help with dissipating the heat from the primary and secondary side which is very good. There's a small PCB where the AC receptacle and power switch are installed which also holds the first part of the EMI suppression filter. So the input filtering begins on this small PCB that has some X and Y capacitors attached to it and then trails onto the main PCB for completion. The EMI filter capacitor is directly soldered to the rear of the socket with a small circuit board.

The Focus SGX 650W power supply supports the following protections:

  • Total Power Protection (OPP): PSU shuts down if the total output power exceeds the maximum rated capacity.
  • Over Voltage Protection (OVP): PSU shuts down if the voltage at any rail exceeds specification.
  • Under Voltage protection (UVP): PSU shuts down if the voltage at each rail drops below specification.
  • Over Current Protection (OCP): PSU shuts down if any of the rails are overloaded by the current.
  • Short Circuit Protection (SCP): PSU shuts down if a short circuit is detected.
  • Over Temperature Protection (OTP): PSU shuts down if the temperature reaches a certain level.

Seasonic Focus SGX 650W PCB

Internally, the Focus SGX 650W is featuring a half bridge LLC topology and LLC resonant converter on the primary side while the secondary side uses synchronous rectification and DC-to-DC converters which provides a greater stability and maximizes the output of the 12V rail.

All of the filtering is handled by several Nippon Chemi-Con capacitors which is great. Seasonic has replaced the use of cables with a copper plate to connect the modular panel to the PCB, drastically reducing the possibility of production errors during manual insertion, as well as improving the quality of the output power in general.

Seasonic Focus SGX 650W panel

Looking at the back of the power supply, we can see a nice, clean layout which can be very helpful for people who are new to building their own systems. The modular panel includes 8 sockets and the panel is nicely labeled to let you know what each socket is used for. Most users will not need to plug in all of their modular cables so it's perfectly normal to have extra cables left unplugged.

Seasonic Focus SGX 650W Gold fan

The 120mm Fluid Dynamic Bearing (FDB) fan has a maximum of 2000 RPM and is rated for 0.45A at 12V. Fluid dynamic bearings fans have a much longer lifespan compared to ball bearing fans and generate less operational noise and heat. Also, fluid dynamic bearings use lubrication on the surface to reduce friction and vibration.

The fan is made by Globe Fan and the model number is S1201512HB and it is connected to the PCB using a 2-pin connector. Life expectancy of the fan is estimated to be up to 50,000 hours working at an average temperature of 40° C. The fan does a good job of dissipating the heat and Seasonic includes a metal grid which is designed to protect the fan from objects that may obstruct its operation.

Test Methodology

Our goal here is to simulate realistic loading conditions to see how well the PSU can maintain the various output voltages while operating under different loads. All of the testing is conducted at an ambient temperature of 22°C. These tests will be performed at several load levels, from low (100W) to high (650W) or higher depending on the PSU. We are looking for results as close to 12V, 5V and 3.3V as possible. We are also measuring the PSU noise levels during our load testing. Sound pressure level readings were measured from about 100cm away from the PSU.

Below is a table listing the tolerances for each power supply voltage rail based on the ATX specification version 2.2. We have also included a table with various dBa ratings to help describe the various noise levels based on real world situations.

Power Supply Voltage Tolerances
RailToleranceMin. VoltageMax. Voltage
+3.3V± 5% (±0.165V)+3.135V+3.465V
+5V± 5% (±0.25V)+4.75V+5.25V
-5V± 10% (±0.50V)-4.50V-5.50V
+12V± 5% (±0.60V)+11.40V+12.60V
-12V± 10% (±1.20V)-10.80V-13.20V

Noise Levels (dBA)
Lawn Mower90 dBA
Vacuum Cleaner80 dBA
City Traffic75 dBA
Conversation65 dBA
Air Conditioning60 dBA
Floor Fan50 dBA
Electric Hum45 dBA
Refrigerator Hum40 dBA
Rustling Leaves30 dBA
Pin Falling15 dBA
Just Audible10 dBA
Threshold of Hearing0 dBA


Seasonic Focus SGX 650W Gold Load Tests
DC Load+3.3V+5V+12VEfficiencyFan SpeedPSU Noise
100W3.31V5.02V12.04V86.3%0 RPM<20 dBA
150W3.29V5.04V12.05V87.8%0 RPM<20 dBA
350W3.31V5.01V12.02V89.1%743 RPM35 dBA
450W3.30V5.03V12.01V90.8%892 RPM36 dBA
550W3.32V5.03V12.04V91.2%1395 RPM37 dBA
650W3.30V5.03V12.06V89.7%1703 RPM40 dBA

The Focus SGX 650W delivered great results just as we expected. All three main rails ran flawlessly during our tests and the minimal variations were all within the strict 5% tolerance limit. Thanks to the hybrid fan mode, the Focus SGX 650W is silent in low loads due to the fan not spinning and even during medium loads like gaming it is still very quiet. The fan does become somewhat noticeable during high loads but it is definitely bearable. If you use your computer primarily for browsing the web, gaming and watching movies then you will most likely never hear the fan spinning because the fan turns off when the PSU load is under 30%.


For those looking to purchase a quality SFX-L PSU, the Focus SGX 650W from Seasonic is an excellent choice. The build quality is fantastic and the integration quality is top-notch as we have come to expect from Seasonic. It sports a clean and elegant build quality that has ample power to drive a high end gaming computer with no problem.

The test results were great and the voltage regulation was excellent. It features a single +12V rail that can deliver up to 54A (648W) on the +12V output which is enough power to feed a high-end graphics cards while still having plenty of room left for overclocking the CPU. The trend for small form factor computers has been increasing over the years due to the hardware components becoming more efficient and Seasonic is helping to drive the efficiency movement by releasing the Focus SGX series of power supplies.

The Focus SGX 650W comes packaged with everything that you would need to build a high-end system. It includes an SFX-to-ATX adapter for users who may want to mount it in an ATX case to improve the airflow inside the case. The 120mm FDB fan features an intelligent fanless operation mode that makes it great for quiet home or office use and if the loading condition is below 30%, the fan will remain off for silent operation.

+ Well-Priced
+ Quiet FDB Fan
+ Fully Modular
+ 10 Years Warranty
+ Great Build Quality
+ SFX-to-ATX Adapter

- No Fan Switch

The Focus SGX 650W is an excellent power supply that performs exactly as advertised and the $120 price-tag is quite reasonable for a quality SFX-L PSU such as this one. The 10 years warranty shows how confident in the quality and reliability of their product Seasonic is. If you are in the market for a top notch SFX-L PSU, I highly recommend checking out the Focus SGX 650W. Overall, the Seasonic Focus SGX 650W deserves our gold award.

Final Score    9.7

RelaxedTech Editor's Choice