XFX 750 W Black Edition Power Supply Review
Load Tests
Contents
We conducted several tests with this power supply, as described in the article Hardware Secrets Power Supply Test Methodology.
First we tested this power supply with five different load patterns, trying to pull around 20%, 40%, 60%, 80%, and 100% of its labeled maximum capacity (actual percentage used listed under “% Max Load”), watching how the reviewed unit behaved under each load. In the table below we list the load patterns we used and the results for each load.
If you add all the power listed for each test, you may find a different value than what is posted under “Total” below. Since each output can vary slightly (e.g., the +5 V output working at +5.10 V), the actual total amount of power being delivered is slightly different than the calculated value. On the “Total” row we are using the real amount of power being delivered, as measured by our load tester.
The +12VA and +12VB inputs listed below are the two +12 V independent inputs from our load tester. Since the reviewed unit has a single +12 V rail, both inputs were connected to the power supply single +12 V rail (+12VB was connected to the power supply EPS12V connector and all other cables were connected to the load tester +12VA input).
| Input | Test 1 | Test 2 | Test 3 | Test 4 | Test 5 |
| +12VA | 5 A (60 W) | 11 A (132 W) | 16 A (192 W) | 22 A (264 W) | 27 A (324 W) |
| +12VB | 5 A (60 W) | 10 A (120 W) | 16 A (192 W) | 21 A (252 W) | 27 A (324 W) |
| +5V | 2 A (10 W) | 4 A (20 W) | 6 A (30 W) | 8 A (40 W) | 10 A (50 W) |
| +3.3 V | 2 A (6.6 W) | 4 A (13.2 W) | 6 A (19.8 W) | 8 A (26.4 W) | 10 A (33 W) |
| +5VSB | 1 A (5 W) | 1 A (5 W) | 1.5 A (7.5 W) | 2 A (10 W) | 2.5 A (12.5 W) |
| -12 V | 0.5 A (6 W) | 0.5 A (6 W) | 0.5 A (6 W) | 0.5 A (6 W) | 0.5 A (6 W) |
| Total | 149.8 W | 302.6 W | 454.6 W | 605.4 W | 755.9 W |
| % Max Load | 20.0% | 40.3% | 60.6% | 80.7% | 100.8% |
| Room Temp. | 44.2° C | 43.4° C | 45.7° C | 48.7° C | 48.9° C |
| PSU Temp. | 42.3° C | 44.1° C | 45.9° C | 47.9° C | 50.8° C |
| Voltage Stability | Pass | Pass | Pass | Pass | Pass |
| Ripple and Noise | Pass | Pass | Pass | Pass | Pass |
| AC Power | 174.2 W | 343.8 W | 520.9 W | 704.0 W | 898.0 W |
| Efficiency | 86.0% | 88.0% | 87.3% | 86.0% | 84.2% |
| AC Voltage | 113.7 V | 112.2 V | 110.3 V | 108.6 V | 105.8 V |
| Power Factor | 0.965 | 0.973 | 0.978 | 0.981 | 0.980 |
| Final Result | Pass | Pass | Pass | Pass | Pass |
XFX 750 W Black Edition, like Seasonic M12D and S12D, achieved very high efficiency, staying above 84% all times, including when you pull its maximum labeled power. If you pull between 40% and 60% from its labeled capacity (i.e., between 300 W and 450 W) you will get efficiency between 87% and 88%.
This unit has 80 Plus Silver certification, and in theory would present efficiency of at least 85% at light (20%) and full (100%) loads and 88% at typical (50%) load. Our tests are tougher than the ones conducted by Ecos Consulting (the company behind 80 Plus certification) because they test power supplies at 23° C, while we test them at double this temperature, and the higher temperature is, the lower efficiency is. That is why we got efficiency below 85% during full load (test five).
Voltage stability was another highlight from XFX 750 W Black Edition, with all voltages inside 3% of their nominal values(i.e., voltages were closer to their nominal value than needed, as ATX spec allows voltages to be up to 5% from their nominal values, 10% for -12 V). This includes the -12 V output, which usually doesn’t like to stay within a tolerance this tight.
And finally we have noise and ripple, which were low all the time: noise level at +12 V was below 30% of the maximum allowed. Below you can see the results for test number five. As we always point out, the limits are 120 mV for +12 V and 50 mV for +5 V and +3.3 V and all numbers are peak-to-peak figures.
Figure 19: +12VA input from load tester at 755.9 W (27.2 mV).
Figure 20: +12VB input from load tester at 755.9 W (35.6 mV).
Figure 21: +5V rail with power supply delivering 755.9 W (18.6 mV).
Figure 22: +3.3
V rail with power supply delivering 755.9 W (18.4 mV).
Now let’s see if we could pull more than 750 W from this unit.