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 Picoscope 3424 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 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 50°C.

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) 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 IRP-GOL900 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 IRP-GOL900. 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 very high during all load tests, regardless the relative high operating temperatures. The peak efficiency was registered at 40% of max rated capacity and almost reached 91.5%. Voltage regulation was another pleasant surprise with +12V registering 1.27% deviation and 5V an impressive 1.43%, currently the smallest deviation we have ever measured at this rail. The 3.3V rail didn't perform bad either since it stayed below 3.5%. Regarding PF readings, contrary to efficiency and voltage regulation these weren't so good since with 20% load PF is under 0.9. However with 115V input power PF will be higher and it will most likely exceed 0.9, so it will meet the 80 PLUS Gold requirements. Finally, the CL1 test revealed a problem at 3.3V but we should take into account that no modern PC will ever draw 20A from this rail.

Efficiency at Low Loads

In the next tests, we measure the efficiency of IRP-GOL900 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, 60, 80 and 100W (for PSUs with over 500W capacity). This is important for scenarios in which a typical office PC is in idle with power saving turned on.


Efficiency at low loads is quite high, considering that we have a 900W unit here. From 60-100W efficiency is constantly over 80% and even with only 40W load efficiency manages to stay well above 70%.

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.


Throughout all loads we dialed at the above tests, the 5VSB rail managed to surpass the equivalent thresholds that ATX spec recommends. Overall fairly decent performance here.

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).


As you can see, in idle the PSU consumes quite a lot of power and we are pretty sure that its cooling fan is highly responsible for this. On the contrary, in standby, vampire power is only 0.45W, so the PSU easily meets the ErP Lot 6 requirements.