Seasonic G Series 550 W Review 22

Seasonic G Series 550 W Review

Cross Load Tests »


Using the efficiency results from the previous page, we plotted a chart, showing efficiency of the G-550 at low loads and at loads equal to 20-110% of the PSU's maximum rated load.

For a discussion of these results, see the text at the end of the previous page.

Efficiency at Low Loads

In the next tests, we measured the efficiency of the G-550 at loads much lower than 20% of its maximum rated load (the lowest load that the 80 Plus Standard measures). The loads that we dialed were 40, 60, 80, and 100 W (for PSUs with over 500 W of capacity). This is important for settings where the PC is in idle mode with power saving turned on.

Efficiency at Low Loads
Seasonic SSR-550RM
Test #12 V5 V3.3 V5 VSBPower

At low loads, this unit competes well in its field and, as you can see, achieves very high efficiency with even only 40 W of load. This is one of the benefits of using a small PSU. Minimal energy is wasted even at low loads. You should, as such, carefully examine the power needs of your system in order to pick the right capacity PSU. This will, besides saving money, make sure your system runs as efficiently as possible at low loads.

5VSB Efficiency

The ATX spec states that the 5VSB standby supply's efficiency should be as high as possible and recommends 50% or higher efficiency with 100 mA of load, 60% or higher with 250 mA of load, and 70% or higher with 1 A or more of load. We will take four measurements: three at 100, 250, and 1000 mA, and one with the full load that the 5VSB rail can handle.

5VSB Efficiency
Seasonic SSR-550RM
Test #5VSBPower (DC/AC)EfficiencyPF/AC Volts

5VSB efficiency is definitely not amongst the best we have ever seen, but it is still high overall and meets the ATX spec requirements easily.

Power Consumption in Idle & Standby

In the table below, you will find the power consumption and the voltage values of all rails (except -12V) while the PSU is in idle mode (powered on without any load on its rails) and the power consumption when the PSU is in standby mode (without any load at 5VSB).

Idle / Standby
Seasonic SSR-550RM
Mode12 V5 V3.3 V5VSBPower (AC)PF/AC Volts

The G-550 is ERP Lot 6 2010 and 2013 compliant since it only consumes 0.26 W at standby.

Fan RPM & Delta Temperature

The following chart illustrates the cooling fan's speed (RPMs) and the delta difference between input and output temperature. The following results were obtained at 40°C - 45°C ambient.

Next Page »Cross Load Tests
View as single page
Copyright © 2004-2021 All rights reserved.
All trademarks used are properties of their respective owners.