SilverStone ST45SF V3 SFX 450W PSU Review

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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 is a breath away from 17ms, so we're giving SilverStone a pass. The power-good signal drops before the rails go out of spec, though, according to the ATX spec, it should be at least 1ms away from the actual hold-up time.

Inrush Current

For details on our inrush current testing, please click here.

The small NTC thermistor doesn't do a very good job at limiting inrush current; our measurement is way too high for a low-capacity PSU.

Load Regulation And Efficiency Measurements

Our first set of tests reveals the stability of the voltage rails and the ST45SF'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. 

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Test #12V5V3.3V5VSBDC/AC (Watts)EfficiencyFan SpeedFan NoiseTemps (In/Out)PF/AC Volts
11.911A1.966A1.956A0.971A44.77780.270%1050 RPM17.5 dB(A)38.14°C0.964
24.853A2.959A2.945A1.166A89.74285.431%1050 RPM17.5 dB(A)38.42°C0.981
38.153A3.464A3.459A1.365A134.90486.886%1050 RPM17.5 dB(A)38.94°C0.985
411.450A3.963A3.944A1.565A179.76186.936%1250 RPM19.0 dB(A)39.65°C0.988
514.418A4.969A4.946A1.766A224.78486.555%1640 RPM24.5 dB(A)40.61°C0.990
617.393A5.973A5.954A1.970A269.75686.010%2050 RPM29.8 dB(A)41.51°C0.991
720.374A6.987A6.968A2.170A314.75185.591%2350 RPM35.0 dB(A)42.17°C0.995
823.365A7.999A7.985A2.375A359.69684.762%2675 RPM37.5 dB(A)43.04°C0.995
926.797A8.516A8.523A2.380A404.72483.969%2750 RPM40.5 dB(A)43.86°C0.993
1029.978A9.046A9.030A2.995A449.57782.823%2765 RPM41.1 dB(A)44.96°C0.991
1133.771A9.061A9.050A3.000A494.52281.766%2785 RPM41.5 dB(A)45.63°C0.987
CL10.098A13.019A13.003A0.004A109.72079.906%1680 RPM25.3 dB(A)42.86°C0.983
CL237.472A1.004A1.002A1.002A463.53083.791%2750 RPM40.5 dB(A)44.22°C0.991

Load regulation at +12V is quite tight, given this PSU's SFX form factor. At 5V and 3.3V, it remains within 3%. That's decent.

The small fan is quiet up to 1050 RPM. And even at full speed it's not as noisy as we expected. SilverStone's fan profile gets aggressive during the sixth test. An operating temperature over 41°C forces it to work hard, keeping the PSU's internals from overheating.

Finally, we observe low efficiency levels compared to PSUs with higher efficiency certifications. But don't forget that this is a budget-oriented power supply.

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Contributing Editor

Aris Mpitziopoulos is a Contributing Editor at Tom's Hardware US, covering PSUs.