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 45-50°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 EPM1500EGT 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 EPM1500EGT. 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.


As you can see, the main asset of EPM1500EGT, besides its huge capacity, is the high efficiency. Even with 20% load we measured over 91% efficiency and until 60% load efficiency stayed at very high levels, proving that this unit can easily compete with the other, lower capacity, Platinum models. From 80% load, efficiency started to decrease but we must keep in mind here the high operating temperatures we conducted our tests at. In fact it is amazing to see a unit delivering 1500W of power with over 45°C ambient and still retain over 88.5% efficiency. However everything in this life comes at a cost and in this case the cost is the loose voltage regulation on the +12V rail which is close to 5%. Thankfully the 5V rail holds relative good voltage regulation but 3.3V are on the loose side too. Apparently you can't have it all, ultra high capacity, over 90% efficiency and tight voltage regulation. Some compromises have to be made, but to speak frankly we would prefer slightly lower efficiency, if this would lead to improved +12V regulation.

Efficiency at Low Loads

In the next tests, we measure the efficiency of EPM1500EGT 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.


At low loads the results are surprisingly good, considering the huge capacity of the unit. Only with 40W load efficiency drops below 70% while at the other three tests it is at high levels reaching an impressive 82.61% with 100W load. This giant can work pretty efficient at low loads too and this is an outstanding feature.

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.


The 5VSB rail is not as strong as we would like it to be, but it definitely is very efficient. This is one of the very few times that we measure over 80% efficiency in 5VSB at tests #3 and #4. Very good job here Enermax!

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).


Energy consumption at standby is restricted to 0.21W so this unit passes with flying colors, when looking at the ErP Lot 6 2010 requirements (and the future 2013 ones).