1. Place the Seasonic power supply into the correct place provided in the computer case and secure it to the back panel with the four mounting screws that were provided in the accessory bag of the packaging.  Do not over tighten the screws.
  2. Depending on the type of your computer case, correct mounting of the power supply in most cases will result with the fan side top cover facing the mainboard. This does not necessarily apply to all types of cases. (How to correctly position the power supply)
  3. Mainboard Connection:
    1. DO NOT force the connector into place; the connectors are “keyed” so they can only fit one way. Make sure the connector lock is secure.
    2. Connect the power supply end of the 24/20 Pin convertible connector to the appropriate receptor on thepower supply unit.
    3. Connect the power supply end of the 24/20 Pin convertible connector to the appropriate receptor on thepower supply unit.
    4. Connect the +12 V P4 connector and the EPS +12 V connector, if applicable.
    5. If your system requires dual EPS +12V connectors, please connect the 12-pin end of the second CPU 8-pin connector into the appropriate 12-pin receptor on the power supply unit. Then connect the mainboard end of this 8-pin connector to the mainboard.
    6. NOTE: Cables out of the box might be rigid due to storage temperature, which might make cable management a bit difficult. You can use a hair dryer to carefully warm up the cables so they are more flexible and easier to install and manage.
  4. The hybrid fan control selector switch, located on the modular cable panel side of the power supply unit can be set to either “I” – S2FC (Normal Fan Control without Fanless Mode) or “O” – S3FC (Hybrid Silent Fan Control with Fanless Mode).
    1. The Normal Fan Control setting (“I”) enables the fan to rotate continuously in Silent Mode and CoolingMode, depending on the system load.
    2. The Hybrid Silent Fan Control setting (“O”) enables the power supply to run in Fanless Mode up to 20 % (± 5 %) of the maximum rated load. When the load further increases, the S3FC fan control will keep regulating perfect cooling through the Silent Mode or Cooling Modes.

There are some graphics cards on the market that are outfitted with two or three PCIe slots. The power consumption of such cards is usually more than 225 watts, therefore customers must use two separate PCIe cables to safely connect them to the power supply.

PCIe Remark DO

It is very important to use a separate PCIe cable per slot with only one of the connectors attached to the GPU.

PCIe Remark Dont

Seasonic’s new fan control concept is the best choice for silent PC enthusiast. Seasonic believes power supply fans should not rotate as fast as they could but should be in operation as little as possible to preserve energy and create the most silent possible working environment.

The most important advantages and benefits of this Seasonic-patented fan control system are:

  • Reducing noise without increasing temperature
  • Extending fan life by eliminating unnecessary rotations
  • Optimizing heat dissipation at all times

New hysteresis chart

The fan control button can be found on the back of the back of the FOCUS PLUS power supply, next to the power switch. The image here illustrates how to select different fan control modes to suit your need.

DO NOT press the button if you wish to include the Fanless Mode, which means the fan in the power supply will not spin when the power supply is under light loads. Press the button if you wish to have the fan spin at all times, even at lower loads.


Some may refer to DC-to-DC converter design as “Voltage Regulator Modules for the 3.3 V and 5 V lines”. DC-to-DC conversion achieved directly from the main 12 V DC line eliminates the need for additional transformer and brings higher efficiency and immediate response for the computer system. Instead of using two or more AC to DC transformers, a single high quality and capacity AC to 12 V DC transformer is applied to drop the AC voltages to low DC voltages suitable for computers. All the other DC voltages rails are derived from the 12 V DC line using DC to DC conversion.

What are the benefits of the DC-to-DC converter design?

  1. High compatibility with zero minimum loads on each line.
  2. Better cross regulation.
  3. Maximum capacity of the 12 V current for extreme utilization
  4. Higher efficiency and better dynamic response.
Seasonic recommends a UPS with a pure sinewave output; however, a high quality simulated sinewave UPS from a reputable manufacturer could also be a possible solution to be used with our power supplies.

Power factor is the relationship between working (active) power and total power consumed (apparent power), expressed as the ratio of true AC input power to the apparent ac input power. Essentially, power factor is a measurement of how effectively electrical power is being used. A higher power factor represents a more effective use of electrical power. Power Factor Correction on a switching power supply controls the timing and wave shape of the input current drawn to maintain the current waveform approximately in phase with and of the same shape as the line voltage. This results in a power factor of approximately 1.0. This is important when electronic equipment consumes a significant amount of power, since otherwise the facility power system could exceed its current ratings for the power consumed and potentially impact other equipment on the same power system.

In average electronic equipment without PFC function, the PF is around 50 % only.

Active power factor correction is used to correct the power factor for non-linear loads. While passive PFC uses inductors or capacitor circuitry to reduce harmonic current, the maximum power factor stays only around 0.75. Non-linear PFC, however, employs active components (control circuitry and power sine conductor On/Off switch) to adjust the input current wave-form to simulate the input voltage wave form to achieve efficiency figures of 0.95 or even higher. With APFC, the input voltage of the power supply increases to range between 90 V DC and 264 V DC, which eliminates the need of an additional voltage selector switch on the power supply. These universal voltage models add flexibility in usage and extra value to the product. Other benefits of APFC include a larger buffer to EN harmonics requirement to ensure compliance and more efficient energy utilization.

A good power supply lasts several years and comes with a variety of connectors that should cover all your needs. Modular cables provide more flexibility in usage and connectivity and at the same time enable you to manage your cables neatly inside the computer case. Less unnecessary cables to tuck away in the case also mean that the ventilation of your system becomes less obstructed. A properly ventilated system will protect your components from overheating and will extend their lifetime.

This missing pin is not a defect of your power supply. In the past, this place in the main power connector was to support the –5 V output. Nowadays this output is no longer necessary for modern PC’s. According to Intel’s Power Supply Design Guide however, this pin should be kept empty to comply with the specifications.

You may have noticed that in our texts we use different spellings for Seasonic. In case you have been wondering, here is why:

Sea Sonic – is an abbreviated form of our company name Sea Sonic Electronics Co., Ltd

Seasonic – is the brand name of the power supplies made by Sea Sonic.

Start your Seasonic RMA directly.

Seasonic warranty information.  – Learn more about the warranty period and Seasonic RMA procedure.