Test Setup

All measurements are performed utilizing ten electronic loads (seven Array 3711A, 300W each, and three Array 3710A, 150W each), which are able to deliver over 2500W of load and are controlled by a custom made software. We also use a DS1M12 (Stingray) oscilloscope, a CHY 502 thermometer, a Fluke 175 multimeter and an Instek GPM-8212 power meter. Furthermore, in our setup we have included a wooden box, which along with a heating element is used as a Hot Box. Finally, we have at our disposal two more oscilloscopes (Rigol 1052E and VS5042) 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.

Voltage Regulation Charts

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

Efficiency Chart

In this chart you will find the efficiency of AU-750M at low loads and at loads equal to 20-100% of PSU’s maximum rated load.

Voltage Regulation and Efficiency Measurements

The first set of tests reveals the stability of voltage rails and the efficiency of AU-750M. The applied load equals to (approximately) 20%, 40%, 50%, 60%, 80% and 100%, of the maximum load that the PSU can handle. In addition, we conduct two more tests. In the first we stress the two minor rails (5V & 3.3V) with the maximum load that our tester can apply to these rails, while the load at +12V is only 2A and in the second test we dial the maximum load that +12V can handle while load at minor rails is minimum.


Although efficiency is pretty high, we were not satisfied wit the results. Only the 5V rail managed to stay within 3% while +12V exceeded this limit and 3.3V went even beyond 5%. Voltage regulation on the last two rails definitely needs tuning. Also the results at full load and Cross Load tests weren't the ones we expected. Judging from the voltage readings on all rails and especially at +12V it seems that the PSU struggles to deliver 750W of power. Especially at CL2 the above-mentioned rail dropped its voltage to very low levels, under 11.5V, something simply unacceptable for a PSU of this price/category.

Efficiency at Low Loads

In the next tests, we measure the efficiency of AU-750M at loads much lower than 20% of its maximum rated load (the lowest load that the 80 Plus Standard measures). The loads that we dial are (approximately) 40, 65 and 90W. This is important for scenarios in which a typical office PC is in idle with power saving turned on.


Efficiency at low loads is the strength of the AU-750M as it seems, since in two out of the three tests the 80% mark was easily surpassed.

5VSB Efficiency

ATX spec states that the 5VSB standby supply's efficiency should be as high as possible and recommends 50% or higher efficiency with 100mA load, 60% or higher with 250mA load and 70% or higher with 1A or more load.
We will take four measurements, at 100 / 250 / 1000 mA and 3000 mA.


The 5VSB exhibited an astonishing efficiency. With 0.1A load, efficiency is 20% above the ATX recommended level and with 3A we measured very close to 90% efficiency!

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 (On but without any load at its rails) and the power consumption when the PSU is in standby (without any load at 5VSB).


Phantom power is really low, among the lowest we have ever measured, so the AU-750M will not have any problem meeting not only the current ErP Lot 6 2010 requirements, but all future ones too.