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. Furthermore, in our setup, we included a wooden box, which, along with a heating element, was used as a hot box. 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. In this article, you will find more details about our equipment and the review methodology we follow. Finally, if the manufacturer states that the maximum operating temperature of the test unit is only 40°C, then we try to stay near this temperature; otherwise, we crank up the heat inside the hotbox up to 45-50°C.

Voltage Regulation Charts

The following charts show the voltage values of the main rails, recorded over a range from 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 AX1200i 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 AX1200i. 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. In the second test, we dialed the maximum load that the +12V rail could handle, while the load on the minor rails was minimal.


Before we start the analysis of this test session result, we should note that the numbers in parenthesis, of the table above, show the readings that we took from the Corsair Link program. In some cases the readings were very accurate, but some others were way off. However Corsair states, in the program's user guide that due to the accuracy swings at low loads, the overall efficiency may occasionally display inaccurate results such as 80% or 100%. They also state that this is due to a limitation in the monitoring technique and does not imply a problem with the power supply.
Now let's skip to the results that we obtained through our equipment. As you can see the PSU delivered its full power, flawlessly, even at over 50°C operating temperatures. Voltage regulation on all rails, especially at +12V, was tight, and efficiency in seven out of the eight load tests we ran for this session, exceeded 90%. All in all, the PSU proved that it is a solid performer that aims directly at the top of its category. Also, a note here about the output noise. As you will notice from the table above, the fan didn’t spin at all up to 40% load - the PSU was totally inaudible. During the next two tests it spun at really low RPMs. Only at 80% load test and afterwards with temps up to 50°C, did the fan significantly increased its speed without being annoyingly loud. This was one of those rare times we test a high capacity unit, which doesn't wake the neighbors once highly stressed at extra high ambient.

Efficiency at Low Loads

In the next tests, we measured the efficiency of the AX1200i 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 is fairly good, especially if we take into account the high capacity of the unit. With a 40W load, the PSU registered well above 70% efficiency, while with a 60W load, it reached 80%. At the last two tests, it easily managed to surpass the foregoing mark proving that, even at such low loads, it still performs efficiently.

Corsair Link Screenshots

Several screenshots of the Corsair Link software, which we took during the above test sessions, can be found below. The order of the screenshots is the same with the order of the tests shown on the previous two tables (20% load test — Cross-load 2, low loads efficiency test #1 — test #4).

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 manages to register very high efficiency readings even with very low loads. In Test #1, efficiency surpasses 70% and in the last two tests it is above 80% - a very high level for this particular rail. On top of that, voltage regulation at 5VSB is among the best we have ever seen at this rail.

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).


Vampire power is very low on the AX1200i and close to the one tenth of the ErP Lot 6 2010 directive. This, of course, means less energy losses and a greener environment!