Seasonic M12D 750 W 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 +12V1 and +12V2 inputs listed below are the two +12 V independent inputs from our load tester. During this test +12V1 input was connected to the power supply +12V1 rail and the +12V2 input was connected to the power supply +12V2 rail.
| Input | Test 1 | Test 2 | Test 3 | Test 4 | Test 5 |
| +12V1 | 5 A (60 W) | 11 A (132 W) | 16 A (192 W) | 22 A (264 W) | 27 A (324 W) |
| +12V2 | 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 | 149.1 W | 299.0 W | 450.1 W | 601.0 W | 750.4 W |
| % Max Load | 19.9% | 39.9% | 60.0% | 80.1% | 100.1% |
| Room Temp. | 48.0° C | 47.9° C | 47.9° C | 46.0° C | 47.4° C |
| PSU Temp. | 42.3° C | 45.2° C | 46.9° C | 49.0° C | 51.2° C |
| Voltage Stability | Pass | Pass | Pass | Pass | Pass |
| Ripple and Noise | Pass | Pass | Pass | Pass | Pass |
| AC Power | 165 W | 326 W | 495 W | 677 W | 868 W |
| Efficiency | 90.4% | 91.7% | 90.9% | 88.8% | 86.5% |
| Final Result | Pass | Pass | Pass | Pass | Pass |
Seasonic M12D 750 W achieved very high efficiency, staying above 90% if you pull up to 60% from its labeled power (450 W). At 80% load (600 W) it presented 88.8% efficiency and at full load (750 W) it could still show efficiency above 85%, which is terrific.
Voltage stability was another highlight from Seasonic M12D 750 W, 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 this tight tolerance.
And finally we have noise and ripple, which were low all the time: noise level at +12 V was below 20% 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: +12V1 input from load tester at 750.4 W (22.4 mV).
Figure 20: +12V2 input from load tester at 750.4 W (23.4 mV).
Figure 21: +5V rail with power supply delivering 750.4 W (13.6 mV).
Figure 22: +3.3 V rail with power supply delivering 750.4 W (16.6 mV).
Now let’s see if we could pull more than 750 W from this unit.