Test Setup

All measurements were performed using ten electronic loads (seven Array 3711A [300 W each] and three Array 3710A [150 W each]), which are able to deliver over 2500 W of load and are controlled by a custom-made software. We also used a Picoscope 3424 oscilloscope, a CHY 502 thermometer, a Fluke 175 multimeter, and an Instek GPM-8212 power meter. We also included a wooden box, which, along with a heating element, was used as a hot box in our setup. Finally, we had at our disposal four more oscilloscopes (Rigol 1052E and VS5042, Stingray DS1M12, and a second Picoscope 3424) and a CEM DT-8852 sound level meter. You will find more details about our equipment and the review methodology we follow In this article. We conduct all of our tests at 40 - 45°C ambient in order to simulate the environment found inside a typical system with more accuracy; the 40 - 45°C being derived from a standard ambient assumption of 23° with 17 - 22°C added for the typical temperature rise within a system.

Voltage Regulation Charts

The following charts show the voltage values of the main rails, recorded over a range of 60 W to the maximum specified load, and the deviation (in percent) for the same load range.

5VSB Regulation Chart

The following chart shows how the 5VSB rail deals with the load we throw at it.

Efficiency Chart

In this chart you will find the efficiency of the G850-MAS at low loads, and at loads equal to 20-100% of the PSU’s maximum rated load.

Voltage Regulation and Efficiency Measurements

The first set of tests revealed the stability of the voltage rails and the efficiency of the G850-MAS. The applied load was equal to (approximately) 20%, 40%, 50%, 60%, 80%, and 100% of the maximum load that the PSU can handle. In addition, we conducted two more tests. In the first test, we stressed the two minor rails (5V and 3.3V) with a high load, while the load at +12V was only 2 A, and, in the second test, we dialed the maximum load that the +12V rail could handle, while the load on the minor rails was minimal.


Efficiency is high overall, but definitely not ground breaking for a Gold unit. The unit's fan started to spin at low RPMs since we exceeded the 35°C threshold in our first test. Its speed increased during the 50% load test, making it clearly audible with it being quiet noisy during the last two tests. Voltage regulation was tight enough at +12V (for our standards), while it was around average for the PSU's category on the minor rails. The 5VSB rail registered one of the smallest deviations we have ever measured on this rail. In general, the PSU performed fairly well in these tests despite the fact that it uses a plain double forward topology on the primary side and not an exotic full-bridge, or an LLC resonant converter. Gold units that utilize resonant converters still achieve significantly higher efficiency, but also cost more (e.g. the Corsair AX850 or the Seasonic X-850).

Efficiency at Low Loads

In the next tests, we measured the efficiency of the G850-MAS 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 with only 40 W load is disappointing since it dropped below 70%. However, efficiency dramatically increases and manages to pass the 80% mark with only 20 W more on the last two tests.

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.


The 5VSB rail registered amazing efficiency in the first two tests while remaining at good levels with higher loads, which is not that impressive, in the last two tests.

Power Consumption in Idle & Standby

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


LEPA's claims proved to be true. The PSU needs much less than 0.5 W in standby, easily meeting the ErP Lot 6 2013 requirements.