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 70W to the maximum specified load, and the deviation (in percent) for the same load range.

Efficiency Chart

In this chart you will find the efficiency of STR-500 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 STR-500. 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 a high load, 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 minimal.


Efficiency is astonishing. From 40 to 60% load it is constantly above 93%! It is clear that the also platinum LZP-550 is no longer the efficiency king since the STR-500 outperforms it here and easily takes first place. After recovering from the efficiency shock it's time to check the voltage regulation. At +12V it's pretty tight with 1.3% deviation, at 5V a little over 3% and finally at 3.3V it is over 4%. It's obvious that the LZP-550 performed better here. We would like to see the 3.3V rail registering tighter voltage regulation or at least something close to 3%, like the 5V did. But with such high efficiency levels we can easily overlook 3.3V, since it did not exceed 5% and also the low PF readings with 20% load.

Efficiency at Low Loads

In the next tests, we measure the efficiency of STR-500 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 40, 70 and 90W. This is important for scenarios in which a typical office PC is in idle with power saving turned on.


Once more efficiency is crazy high. This PSU doen't care about the load it has on its rails. It will deliver the highest possible efficiency and leave the competition far behind wondering. With 90W load efficiency already reached near 92%!

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, three at 100 / 250 / 1000 mA and one with the full load that 5VSB rail can handle.


At 5VSB efficiency isn't so astonishing as in the previous tests but still is quite high. Only with 0.1A load the recommended by ATX spec mark (50%) wasn't reached but at all other loads efficiency was above recommended levels.

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 way lower than the 1W limit so the unit is ErP Lot 6 2010 ready and it will also pass the future 2013 requirements, which demand lower than 0.5W power consumption in standby.