Load Regulation, Hold-Up Time & Inrush Current
To learn more about our PSU tests and methodology, please check out How We Test Power Supply Units.
Primary Rails And 5VSB Load Regulation
Load Regulation testing is detailed here.
Hold-Up Time
Our hold-up time tests are described in detail here.
The hold-up time we measure is much longer than the ATX spec's required 17ms. Moreover, Seasonic's power-good signal is accurate; it drops before the rails go out of spec.
Inrush Current
For details on our inrush current testing, please click here.
The inrush current is suppressed efficiently by an NTC thermistor.
Load Regulation And Efficiency Measurements
The first set of tests reveals the stability of the voltage rails and the SSR-750FX's efficiency. The applied load equals (approximately) 10 to 110 percent of the PSU's maximum load in increments of 10 percentage points.
We conducted two additional tests. During the first, we stressed the two minor rails (5V and 3.3V) with a high load, while the load at +12V was only 0.1A. This test reveals whether a PSU is compatible with Intel's C6/C7 sleep states or not. In the second test, we determined the maximum load the +12V rail could handle with minimal load on the minor rails.
| Test # | 12V | 5V | 3.3V | 5VSB | DC/AC (Watts) | Efficiency | Fan Speed | PSU Noise | Temps (In/Out) | PF/AC Volts |
|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 4.380A | 1.996A | 1.994A | 0.981A | 74.721 | 85.411% | 0 RPM | <6.0 dB(A) | 42.05°C | 0.955 |
| 12.131V | 5.012V | 3.303V | 5.095V | 87.484 | 38.38°C | 115.20V | ||||
| 2 | 9.797A | 2.992A | 2.999A | 1.180A | 149.732 | 89.414% | 0 RPM | <6.0 dB(A) | 42.62°C | 0.983 |
| 12.132V | 5.008V | 3.299V | 5.083V | 167.459 | 38.80°C | 115.20V | ||||
| 3 | 15.560A | 3.498A | 3.517A | 1.379A | 224.860 | 90.296% | 700 RPM | 14.6 dB(A) | 38.85°C | 0.989 |
| 12.132V | 5.004V | 3.295V | 5.071V | 249.026 | 52.18°C | 115.19V | ||||
| 4 | 21.307A | 4.004A | 4.008A | 1.580A | 299.705 | 90.300% | 550 RPM | 10.4 dB(A) | 39.00°C | 0.991 |
| 12.132V | 5.000V | 3.292V | 5.059V | 331.900 | 53.36°C | 115.19V | ||||
| 5 | 26.716A | 5.002A | 5.014A | 1.780A | 374.628 | 89.703% | 560 RPM | 10.5 dB(A) | 40.37°C | 0.990 |
| 12.134V | 4.996V | 3.288V | 5.045V | 417.633 | 55.25°C | 115.27V | ||||
| 6 | 32.118A | 6.016A | 6.026A | 1.985A | 449.554 | 89.092% | 735 RPM | 15.4 dB(A) | 40.60°C | 0.991 |
| 12.135V | 4.990V | 3.284V | 5.034V | 504.597 | 55.86°C | 115.17V | ||||
| 7 | 37.534A | 7.018A | 7.042A | 2.190A | 524.474 | 88.327% | 1325 RPM | 31.4 dB(A) | 42.34°C | 0.991 |
| 12.133V | 4.986V | 3.279V | 5.019V | 593.787 | 57.82°C | 115.17V | ||||
| 8 | 42.959A | 8.034A | 8.062A | 2.395A | 599.416 | 87.492% | 1960 RPM | 41.4 dB(A) | 43.07°C | 0.992 |
| 12.128V | 4.981V | 3.275V | 5.006V | 685.112 | 59.02°C | 115.16V | ||||
| 9 | 48.809A | 8.539A | 8.586A | 2.400A | 674.436 | 86.791% | 2310 RPM | 45.1 dB(A) | 44.06°C | 0.992 |
| 12.126V | 4.977V | 3.271V | 4.998V | 777.079 | 60.62°C | 115.16V | ||||
| 10 | 54.388A | 9.058A | 9.085A | 3.011A | 749.284 | 85.960% | 2320 RPM | 45.2 dB(A) | 45.87°C | 0.993 |
| 12.127V | 4.973V | 3.268V | 4.977V | 871.661 | 62.27°C | 115.15V | ||||
| 11 | 60.564A | 9.067A | 9.093A | 3.015A | 824.135 | 84.992% | 2320 RPM | 45.2 dB(A) | 47.30°C | 0.993 |
| 12.126V | 4.970V | 3.265V | 4.970V | 969.658 | 65.69°C | 115.15V | ||||
| CL1 | 0.099A | 12.013A | 12.004A | 0.004A | 100.757 | 84.378% | 560 RPM | 10.5 dB(A) | 43.09°C | 0.973 |
| 12.145V | 4.998V | 3.290V | 5.101V | 119.412 | 55.37°C | 115.21V | ||||
| CL2 | 61.936A | 1.005A | 1.002A | 1.001A | 764.309 | 86.243% | 2320 RPM | 45.2 dB(A) | 46.36°C | 0.993 |
| 12.125V | 4.982V | 3.279V | 5.037V | 886.231 | 62.78°C | 115.16V |
Load regulation on the +12V rail is very tight. It's a little looser on the minor rails, but still satisfactory. Only the 5VSB rail comes close to a 3% deviation, so it could be improved upon. When it comes to efficiency, the 80 PLUS Gold specification requires at least 87% efficiency with 20% and 100% of this PSU's max-rated capacity, and 90% efficiency under 50% load. As you can see, the first requirement is met. The PSU comes close at 50% load. However, under full load, there is a >1% difference compared to the desired 87%. As always, though, we run our tests at much higher ambient temperatures than the 80 PLUS organization's unrealistic 23°C levels.
The fan profile gets aggressive once the load and operating temperatures get too high. In our opinion, a larger fan and proper fan profile would solve this problem, enabling the same airflow at lower rotational speeds. Since a 140mm fan is out of the question, Seasonic could try using a 130mm fan like EVGA does with its G3 models.
MORE: Best Power Supplies
MORE: How We Test Power Supplies
MORE: All Power Supply Content