Seasonic Focus Plus Platinum 750 PSU Review: Efficiency On A Budget

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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 we measure is much longer than the ATX spec requires. Moreover, the power-good signal is accurate.

Inrush Current

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

Inrush current is low with 115V input, but quite high with 230V.

Load Regulation And Efficiency Measurements

The first set of tests reveals the stability of the voltage rails and the SSR-750PX’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 SpeedPSU NoiseTemps (In/Out)PF/AC Volts
14.354A1.987A1.986A0.982A74.41686.788%0 RPM<6.0 dB(A)45.15°C0.940
29.761A2.984A2.982A1.181A149.34290.468%0 RPM<6.0 dB(A)45.58°C0.984
315.563A3.481A3.463A1.380A224.85391.505%0 RPM<6.0 dB(A)46.44°C0.992
421.296A3.980A3.977A1.581A299.63791.651%0 RPM<6.0 dB(A)47.71°C0.995
526.703A4.976A4.971A1.782A374.57291.213%445 RPM9.6 dB(A)39.69°C0.993
632.106A5.973A5.970A1.984A449.48390.876%445 RPM9.6 dB(A)40.18°C0.993
737.543A6.967A6.967A2.188A524.79890.141%590 RPM15.2 dB(A)41.44°C0.994
842.984A7.965A7.968A2.392A600.10889.578%1130 RPM29.9 dB(A)42.81°C0.994
948.788A8.467A8.451A2.394A674.65289.227%1655 RPM37.0 dB(A)44.76°C0.995
1054.401A8.967A8.971A3.005A749.87088.598%2005 RPM41.1 dB(A)45.51°C0.995
1160.595A8.968A8.974A3.008A825.10088.041%2025 RPM41.2 dB(A)46.73°C0.995
CL10.740A12.001A11.999A0.000A109.17386.549%485 RPM9.3 dB(A)46.91°C0.973
CL262.013A1.001A1.000A1.000A765.97489.018%2025 RPM41.2 dB(A)45.82°C0.995

Load regulation is great on the +12V rail, just as it was in the similar-capacity Focus Plus Gold PSU. The same goes for the minor rails.

In terms of efficiency, this PSU only satisfies one of the three 80 PLUS Platinum requirements, with 20% of its maximum-rated capacity load. Of course, you already know that we test at much higher temperatures than the 80 PLUS organization, and this greatly affects efficiency.

The fan profile is relaxed indeed; it only exceeds 1000 RPM during test eight, where the load is high and the operating temperature reaches 43°C. During the first four tests, this PSU operates in passive mode without the fan spinning at all.

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Contributing Editor

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