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 XFX Pro 1250W 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 XFX Pro 1250W. 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 and easily clears Gold levels with 115V (estimated 1-1.5% lower efficiency at 115VAC compared to 230VAC). Voltage regulation is tight on all rails, for our testing standards, and the unit easily delivered its full power even at 50°C. As you can see from the "Temp (In/Out)" column with 20% load the PSU was operating in fanless mode so the input temperature at the top side, where the fan is located, was way higher than the output (hot air rises). The fan activated in the middle of test#2 (40% load) and immediately made its presence felt. Actually we didn't expect it to be so noisy and with 50% load things got even worse. We could hear the PSU's fan even during the time that the fans of all electronic loads were spinning and these are really loud. With 100% load we measured 56.1dBA at 0.5m distance from the PSU installed in the hotbox, which has about the same acoustics as a chassis with good airflow. Apparently XFX should look into the loud fan and find a solution either by replacing the fan or by lowering its RPM since the particular PSU has low heat dissipation thanks to its high efficiency. Thankfully in real life scenarios the PSU won't be stressed as much so the fan will spin at lower speeds.

Efficiency at Low Loads

In the next tests, we measure the efficiency of XFX Pro 1250W 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 test#1 is not a good at all, something expected of course from a 1250W PSU. At the other tests efficiency raises above 70% but still cannot surpass the 80% mark. Overall efficiency at low loads is decent but nothing to write home about, especially after we tested the Enermax Platimax 1500W beast which easily passed 80% efficiency with 100W load. Apparently the PSU is tuned for efficiency at higher loads so at such low loads it's like a fish out of water.

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 scored high efficiency overall and at all tests the respective limits were easily passed. With full load at this rail, efficiency reached an impressive 83%, among the highest readings we have ever seen at 5VSB tests.

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).


Vampire power is kept low, at only 0.25W, so the ErP Lot 2010 requirements are easily meet.