Load Regulation, Hold-Up Time, And 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.
Our hold-up time tests are described in detail here.
The hold-up time is much lower than the ATX spec's allowed minimum, and to make matters worse the power-good signal lasts longer than the hold-up time, meaning it drops when the rails are already out of spec.
For details on our inrush current testing, please click here.
The lack of an NTC thermistor inevitably leads to high inrush currents.
Load Regulation And Efficiency Measurements
The first set of tests reveals the stability of the voltage rails and the PSU's efficiency. The applied load equals (approximately) 10 to 110 percent of the maximum load the supply can handle, 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 0.1 A. This test reveals whether a PSU is Haswell-ready 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||Fan Noise||Temps (In/Out)||PF/AC Volts|
|1||5.158A||1.964A||1.961A||0.986A||84.79||89.51%||0 RPM||0 dB(A)||49.34 °C||0.975|
|2||11.340A||2.946A||2.950A||1.185A||169.64||91.97%||0 RPM||0 dB(A)||49.76 °C||0.988|
|3||17.896A||3.448A||3.468A||1.385A||254.78||92.21%||1235 RPM||36.8 dB(A)||39.46 °C||0.995|
|4||24.466A||3.946A||3.956A||1.588A||339.72||92.17%||1350 RPM||38.9 dB(A)||40.24 °C||0.996|
|5||30.707A||4.948A||4.962A||1.791A||424.63||91.81%||1450 RPM||37.6 dB(A)||41.66 °C||0.997|
|6||36.980A||5.944A||5.973A||1.995A||509.58||91.30%||1525 RPM||38.7 dB(A)||42.79 °C||0.997|
|7||43.262A||6.959A||6.988A||2.200A||594.51||90.66%||1565 RPM||41.1 dB(A)||43.86 °C||0.998|
|8||49.573A||7.965A||8.014A||2.404A||679.44||89.87%||1580 RPM||41.9 dB(A)||44.39 °C||0.998|
|9||56.330A||8.482A||8.552A||2.410A||764.41||88.78%||1580 RPM||41.9 dB(A)||45.59 °C||0.998|
|10||62.831A||9.005A||9.070A||3.030A||849.17||88.10%||1590 RPM||42.0 dB(A)||45.77 °C||0.998|
|11||69.973A||9.026A||9.092A||3.035A||934.01||86.96%||1590 RPM||42.0 dB(A)||46.32 °C||0.998|
|CL1||0.099A||14.024A||14.005A||0.000A||119.03||84.14%||0 RPM||0 dB(A)||55.61 °C||0.987|
|CL2||70.782A||1.003A||1.003A||1.001A||868.73||88.40%||1590 RPM||42.0 dB(A)||44.68 °C||0.998|
Load regulation isn't particularly tight compared to the other offerings in this category. As for efficiency, it is much higher with 20% load than required. With 50% load it is very close to 92%, and under full load it falls within 1% of the minimum threshold. We'll give the ST85F-PT a pass since we conduct our tests at very high ambient temperatures.
The unit's fan is deactivated during our first two load tests, keeping the acoustic reading at zero. The fan starts spinning quickly during the third load test, which we'd expect given its 120 mm diameter. Fortunately, the noise isn't bad. Even in a worst-case scenario the ST85F-PT doesn't exceed 42 dB(A). This is the major benefit of using a low-speed fan.